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Differences in ATI X1600 Clock speed in Macs vs PCs,
Overclocking using ATITool in Win XP

Reports last Updated: Aug. 8th, 2007

(from 4/19/2006 news page) A reader posted some info on this back on April 7th, but I didn't pay any attention to it with all the other work (and the fact I don't own an Intel CPU Mac) but after an EEtimes article on the same subject, I checked it out. Here's his post from April 7th:

" ...This might be of interest for those running Boot Camp/XP on an iMac.
I saw a post on the Apple boards about ATITool which will upclock the ati x1600 memory and core speeds.
Apparently the Apple default speed for the 20" (intel) iMac (X1600) is 400/400. The poster said ATITool told him his max was 540/594. He has his at 515/575 and apparently things are OK.
The ATITool is for windows (it's a .exe file). Another good reason to check out Boot Camp.
Any of you with Boot Camp installed on an iMac try ATITools? Benchmarks?
... the tool is here:
http://www.techpowerup.com/downloads/259 (WinXP) ATITool 0.25 Beta 14))
-Jmac "

(BTW - another reader suggested ATI Tray Tools which has a Dynamic overclocking feature but the first report on it said it didn't work for him.) Of course this isn't the first time there's been differences in graphics chip/vram clock speeds in Macs vs PCs (and sometimes there are different GPU/memory variations with different max speed ratings). Although the french page says the MacBook Pro uses the same (Mobility X1600) chip, Apple's iMac specs page doesn't mention the X1600 is a mobility. So I wrote an ATI contact to ask and he said:

" They both use the M56, which is the Mobility part. If you boot the intel iMac into WinXP, the chip is identified as a Mobility Radeon X1600.
The capabilities of the M56 are identical to those of the RV530, which is the desktop equivalent. "

The EEtimes article says a (french) MacBook Pro owner using ATItool showed the X1600 Mobility running at 310MHz core and 278MHz memory clocks, vs 475MHz/470MHz for some other PC X1600 Mobility systems. (A 20in Intel iMac owner said the stock X1600 clocks were 400/400.)
Of course with any overclocking, your mileage may vary and a couple of readers with MacBook Pros here have reported they had problems overclocking the X1600 Mobility in their systems - one reader said he ended up with an unbootable Windows XP, another mentioned freezes when trying to set the clocks. Overclocking also increases power use/heat. (Apple likely chose the lower clock speed for thermal reasons and would probably void the warranty if they knew you overclocked the chip.)

Since ATItool isn't usable for OS X, I wrote the author of the ATICellerator II (dynamic overclocking util for OS X users) to ask if he's planning on an update to support the X1600 chip. I'll post his reply here.

NOTE: The 17in MacBook Pro's X1600 is clocked higher than the 15in model (per reports below). (Update - the new Core2 Duo 15in MacBook Pros also have a higher X1600 clock rate than the original Core Duo 15in models. See reports on the MacBook Pro owner reports page.)

Reader Reports on X1600 Overclocking: (later reports first)
If you've overclocked your Mac's X1600 (either iMac or MBP), let me know your results. Thanks. (Note: Remember that you may not be able to repeat the results of others and there may be negative long-term effects that have not been reported yet.)

(added 8/8/2007)
"I thought it was finally time to overclock (the ATI X1600 in) my new Intel iMac 20" (latest revisions, bought only a few weeks ago.) I was inspired by your page and got amazing results with Ati Tool, so I thought of reporting to to you. Core went from 473 to 585MHz with memory from 495 to 639MHz. They are safe values - they have worked for hours without any graphical corruptions. A bit higher and random yellow polygons begin to appear on the spinning hair cube.

It was about 25% increase in the frame rate and in practice many games I play gained a noticeable boost in FPS, especially at the native resolution 1680x1050, which I prefer to have. To make it even more amazing, none of the fans have yet audibly turned up even though the room ambient is 31 degrees celcius (a warm summer day.)
-Jussi S."

(added 12/19/2006)
"Thanks for your info on over clocking the ATi X1600 for Mac, it helped me quite a lot.
I have a MacBook Pro 15" C2D 2.33GHz (core2 Duo, which has faster clocked X1600), and have WinXP Pro installed under Boot Camp.
Initially when I tried ATITOOLS 0.26 it was showing incorrect values. It says the Core & Mem were set to something like 1,300MHz, and wouldn't allow me to change the values. It also said default was 60/60 (approx).
So I reverted to ATITOOLS 0.25 beta 14 (I think that's the versio linked/used by others here previously-Mike), and she seemed to work correctly. Defaults now being 423/450. I played around for a while, but couldn't get much higher then 500/550 (VPU recovery once, and a system crash once).

After some more looking around, I installed the ATi OmegaDrivers. I then tried using ATITOOLS again, and managed to get a nice 515/575. I played Half-Life 2 - Day of Defeat Source for an hour or so with no problems. Heat wasn't an issue, as I had set the fans to their max of 6,000rpm prior. (i set them with SmcFanControl in Mac OS X, then restarted into Windows, which keeps the fan speed until you shut down).

On a slightly different topic though, I'm a little disappointed with the performance of Day of Defeat Source. Mainly the fact that it stutters every few minutes or so (pauses for a split second). Would you happen to know of any web sites dedicated to gaming on Windows XP through Boot Camp?
Thanks again, cheers.
-Jared H."

Not that I know of but I have not searched for them (don't own an Intel mac and rarely use the home-brew PCs anymore - but when running XP it's basically a PC - general PC game/tweaking sites may have some useful info/tweaks, etc. The system may be throttling down (due to temperatures) - does reducing graphics mode/details, etc. help? (Also check sites on winXP tweaks - like removing background tasks and other tweaks)

(added 11/13/2006)
"3DMark05 performance for MacBook Pro Core 2 Duo, graphics overclocking
I finally installed the 3DMark05 free version into Windows XP on my MacBook Pro Core 2 Duo 2.16Ghz. It's got 2GB RAM.

Default graphics settings, ATI X1600 is clocked at 423Mhz core and 475Mhz memory (Core2 15in MBP has higher X1600 clocks than original 15in Core Duo model, which was around 300MHz) 3DMark05 scores 3870, perfectly decent for an x1600. Overclocked to 500Mhz core, 575Mhz memory, 3DMark05 scores 4449 - that's getting more interesting! (using ATI Tool in WinXP for OC'ing)
My MacBook Pro is absolutely stable at those overclocked settings, I played Oblivion for hours just to be sure. =)
For perspective I gathered the following laptop graphics performance numbers for 3DMark05:
Anything good with integrated Intel GMA950 --------------- 500
Anything good with an ATI X1400 -------------------------- 1800
Anything good with a Geforce 7400 ------------------------ 2000
Anything good with an ATI x700 --------------------------- 2500
MacBook Pro 1.83Ghz (nerfed ATI x1600) ---------------- 2685
Anything good with a Geforce 7600 ------------------------ 3300
Core2 MacBook Pro 2.16GHz (stock clocks) -------------- 3870
Anything good with an ATI X1600 -------------------------- 3900
Core2 MacBook Pro 2.16GHz (OC'd to 500/575) --------- 4449
Anything good with a Geforce 7900GS ---------------------- 6400*
Anything good with aGeForce 7800 GTX ------------------- 7050*
Anything good with a Gefore 7900GTX* -------------------- 8500*
* only available in thicker 17" laptops
-Nicholas M. "

(added 6/26/2006)
"My MacBook Pro's graphics are running steady at 430/430. Anymore than that and it turns off by itself (crashes?). (thermal shutdown I assume-Mike)
With that, I'm now playing WoW at maximum settings and a regular 60fps (in cities). And Half-Life 2: Episode One runs at near 100fps. Now, I'll never game on MacOS again... not even with WoW.
My specs are: CoreDuo 2GHz, 2GB RAM, 100GB 5400RPM HD. Hope this piece of info is useful.

(added 6/26/2006)
"...Just wanted to let you know that ive been running my 2.0 Ghz 15" Macbook Pro at 470/470 for a while. I wanted to run my hardware at what it was meant to be. I've played many games, Oblivion, FEAR, World of Warcraft, and Toca 3. All of these games worked perfect and it almost seemed like it was running cooler at this speed than it would be at the default speed running quake 4 on mac osx. Maybe this is because of the fan speed which does get very loud if things get hot enough but overheating doesn't seem to be an issue.
I know my macbook pro is a rev d and I'm hoping that the thermal grease can handle these speeds. Please tell me any information you might have on this because if this is going to eventually fry then I want to change my speed. Thanks
-Christopher D. "

I can't guarantee there will be no problems from overclocking anything (short or long-term) but normally you'd see problems (freezes, display artifacts, etc.) as a warning sign to reduce speeds. As with any overclocking, you shouldn't do it unless you're willing to accept the potential risks (data corruption/problems, possible hardware failure over time.) Reportedly the X1600 is rated for higher speeds than the stock MBP 15in clocks, but there seems to have been some variation in the heatpipe thermal paste/efficiency as some were not able to run much over the stock clocks without problems. I don't remember any reports of hardware failures so far, but at least one reader reported corrupted file/OS problems.

(added 6/21/2006)
"I'm running stable about 425MHz core / 425MHz memory on my 2.0GHz MacBook Pro playing marathon sessions of Oblivion under Boot Camp (WinXP).
I wish it wasn't playing so well, because I'm not getting anywhere near enough work done.
-Jeff "

(added 6/21/2006)
" I have a macbook pro 15.4" 1.83 with 512 mb of ram and 80gb hd 5400rpm. using bootcamp and winxp and atitool my stable overclock is 430/400 and it runs games great.
However i have noticed that when having atitool open and running the cube , i get an awg framerate of 91fps overclocked , as time goes on though (approx 45min) the awg framerate drops to about 60fps which is actually equivalent to the x1600 running at standard clock settings. I wonder if the chip or system automatically turns down the clock frequency. (Apple notes the CPU speed is variable and may be downclocked depending on temperature, etc. - the MBP 17in also has varible GPU speeds per a report below, but not sure on the 15in-Mike)

An other thing is the heat issue, i have found that after resetting the powermanager as described in an ealier post my system runs much cooler, it used to get so damn hot that i could barely touch the underside, now it just gets lukewarm.
Hope this can help.

More on MacBook Pro 17in ATI X1600 Clock speeds (Variations): (5/15/2006)
(Update: the MacBook Pro user reports/tests/tips page has a 17in Core2 Duo owner's notes on GPU Clock speeds, variations, etc.)

" Mike, In Win XP with the ATITool .25 I get running at Core 418.5 and Memory 445.50 at startup. After reading the post on your site that speeds fluctuate, I have been retesting every 30 min and in various states. Here is what I have recorded; all speeds MHz.

First I let the MBP run unattended for 2 hours no sleep:
Core: 408.2
Memory: 434.73

2 pm:
Core: 376.2
Memory: 400.65

2:30 pm
Core: 353.9
Memory: 376.90

3 pm:
Core: 357.8
Memory: 381.06

Playing QT HD 1080P in XP:
Core: 422.8
Memory: 450.30

Playing Half Life 2:
Core: 398.1
Memory: 423.92

Firefox running MLB.com video:
Core: 372.3
Memory: 396.50

It looks like the GPU can change clock rate with system performance. I can not get the ATItool to report a constant value for periods longer than 45 Seconds roughly. When I tried to lock the Ram and Core to 450Mhz I got a warning stating something like "This video card does not support clock modification." I have a friend that will be getting his 17" MBP this afternoon from the Stonestown Apple Store and were going to bench them tomorrow. I'll shoot you an email once we get XP running. Are there any other Benchmarks you'd like us to run on XP or OSX? Also, as a final note, the 17" MBP runs very hot on the bar between the keyboard and the display. Too hot to touch. I know, I move big 2K Movie lights every day. I am starting to think it's running too hot... More later.
-Adam "

MacBook Pro 17in ATI X1600 Clocked Higher than 15in model? (5/12/2006) Yesterday's news had a MacBook Pro 17in owner's (Adam) comments on performance comparisons and I was curious if the 17in had a different core/memory clock speed on the ATI X1600 than the 15in (which was running much lower than the chip's spec/limits - due to thermal reasons I'm told which may have been related to too much thermal paste on the heatsink). I asked Adam since he mentioned having WinXP installed if he'd run ATITool to see what the 17in's X1600 core/memory clocks were:

" ATITool .25 Beta 14 is running at Core 418.5 and Memory 445.50. (another Windows utility he later said) reports 400Mhz memory. kind of strange.
-Adam "

The powerstep/power saving feature can change CPU speeds and I think on some systems even the GPU speeds. (Update - see Adam's later report above.) Note that Apple has a footnote on MacBook Pro CPU Speeds saying "The MacBook Pro continuously monitors system thermal and power conditions, and may adjust processor speed as needed to maintain optimal system operation".
The MBP 15in X1600 stock core/memory speeds were around 300MHz. There were some differences in reported stock speeds in the past here so I wrote a MBP 15in owner to ask he check the stock speeds using ATItool:

" Here is what I got in XP from ATItools:
On initial open Default Core: 310.50 Default Memory: 297.00
Second open of program: Default Core: 313.00 Memory: 300.00
(his OC results)
Max Core: 353.70 Memory Max: 328.50 Fans Blowing!
Left it all at default, that varies +-3.
PS: looking for a 17" MBP to tear into to check the Thermal application of Paste. Missed one by 20 minutes.
-William R."

First Feedback on ATI Tray Tools (Dynamic Overclocking Util) (see earlier info on Ati tray tools.)

(added 4/27/2006)
"I tried, ATI Tray Tools won't let me overclock my mac book pro. ATITool blows up if the test window is open, but does overclock. I got video to run 450/450. I didn't run it long (just a single run through 3dmark06) so it might not be stable long at that speed or there might be a little more to gain. Going to give it a little WOW work out now.
-Regards, Eric W."

I wonder why it didn't work. (I asked if ATI Tools was removed before trying it in case that matters.) I don't have anything to test ATI tray Tools, but if any reader does, let me know if it works for you. (And just in case it matters, remove ATItools if you already installed it.)

(added 4/26/2006)
"I've overclocked my Macbook Pro x1600. I've been running at 420/420 stably and without any sign of overheating.
I did it to try to improve performance in Oblivion.
The results were hugely successful. I've jumped from a mediocre frame rate at low settings to better (but still slowish) frame rates at medium high settings--native res of 1440x900 with most of the available graphics bling. I running the game with only 512MB RAM, which may explain some performance issues. I have more RAM on the way and am looking forward to seeing if I can get a stable 20+ fps after the upgrade.

The ATI tools beta that is pretty unstable with the drivers apple provides for the x1600. I've heard tell that one can install other drivers but have not myself succeeded. (one older report below mentions omega tweaked drivers)

One thing to note is that the ATITools will crash if the 3d viewer is running when one tries to reset the clock speed.

I have not noticed any serious heat issues. The machine runs hotter, yeah, but cools quickly when processor intensive tasks end. BTW, I don't have a motherboard monitoring tool to get a real check on the core temps of the machine (yeah, I know, bad idea); if you know of one that will work with the MBP, let me know.
Cheers, Lenhart "

I've not searched around for a PC/Windows temp utility but if anyone is using one let me know.

(added 4/26/2006)
"I overclocked my macbook pro as i'm an avid gamer and have done it previously on my old desktop. I had no idea the gpu was so underclocked in this thing. I tested it at 450/459, as I had heard from xlr8yourmac and forums that it seemed to run fine. (Note I mentioned in the first note here (top of page above) that there's risk to this and some had problems. As always YMMV and don't overclock anything if you're not willing to accept the risk of failures/problems. There's never a guarantee on OC'ing or that you can repeat other's results - as you can see from reports here they can vary widely, and some had problems.-Mike)
It did run fine, no problems, but I felt a bit unsafe cranking the thing up by 140mhz, the jump is enormous.

So I changed it to 400mhz, feeling a bit better about that. Everything ran fine for the best two days, never felt hot, it stayed quite cool even when playing CS:S. I had ATI Tools set to OC on boot through the registry so the card wouldn't be played around with too much and it'd just be easier. On one boot however, ATI Tools opened, and crashed immediately, thankfully VPU Recover worked fine and it was alright.
I then attempted to open ATI Tools to check if it was OCed or not. As I opened ATI Tools, the screen went black and the computer did not respond. I restarted it and this time it booted up fine. My friend told me it was likely a bad post, something that can happen when vid cards are OCed. I had this happen previously on my old desktop, so I was not that concerned, just more cautious.
I played a bit more CS:S and upon reflection, decided OCing was just too dangerous for the benefits. I opened ATI Tools (with no problem this time) and turned off the options on startup. It started up fine the next boot, but when I went to check ATI Tools, the screen froze up and my music began looping. I restarted and windows never booted, it sat at a black screen. I then restarted again and booted into mac os x without a problem.

This terrified me, and i'm curious if anyone else has had problems. (yes, some have - see the report from yesterday below (iMac 20in user - noted corrupted windows system.-Mike) I am quite sure my video card is fine, it doesn't seem to be acting funny. I'm positive it is boot camp, xp, and ati tools. And some problem there in.
-Scott "

Dynamic Overclocking Utility: Anyone try this with an Intel CPU Mac w/X1600?

(added 4/25/2006)
" No one has mentioned this, and I don't own a MacIntel to try myself, but there is another excellent o/c tool out there that I use instead of ATITool.
It's ATI Tray Tools, and I've found it's much better and more flexible than ATITool. It allows for DYNAMIC overclocking when 3D APIs are detected. That means that your card is only o/c'd when games, etc. are actually running. Then when the games are done, the gpu/mem speeds are decreased.
(This is the kind of 'dynamic' overclocking (not a constant overclock) that I mentioned before with my OC'd 6800GT (homebrew PC), but I don't have an intel Mac or PC w/ATI card.-Mike)

Granted ATI Tray Tools is a bit more complex, but the early adopters trying this shouldn't have a problem figuring it out. I am more confident in my X800 GTO overclock knowing that it is actually only overclocked when a game is running. This fact will definitely help folks with the heat and battery issues as well.
Website for d/l:
Happy clocking!
(waiting for the day I can afford a new MacIntel tower, w00t!) "

I don't have anything to test ATI tray Tools, but if any reader with an Intel CPU Mac user running XP Tries it, let me know.

(added 4/25/2006)
"These are my results from using ATiTools on my 2Ghz, 2GB, 256MB video, 20" iMac.
My default core/mem setting is 400/400. The tool shows my max core/ mem to be 532/585. I'm currently using the author's recommended setting of 460/470 for my machine. At the 400/400 default I get a 3DMark05 score of 3853. At the 460/470 setting I get a score of 4404.

I've tried two pc games. Half-Life1 and Far Cry. I don't know how to check fps on these, but they're running at the highest setting at my native res of 1680x1050 and look great and run smooth to my eye.

(He later wrote)
An FYI for you guys running ATITools.
I inadvertently crashed my windows system and corrupted the volume with ATITools.

This happened while I was searching for max core and max mem again after doing it originally a week or so before.

For reference, my machine is the 20" iMac, 2.0 Ghz, 2 GB RAM, and 256 MB video.

When I first ran ATITools it showed my default to be the standard 400/400 (398.25/396.00 actual) for my machine.

When I ran find max core/ max mem at that time it came up with 531.90/585.00. If I recall correctly, it only took it some seconds or a minute or so to come up with that data.

When I ran it this time, it was obviously taking much longer, running heat tests and whatever. From watching it run the core test only, I judged it was going to take 20 minutes or more so I left the room. When I came back, the computer was in OS X (my default boot load).

My windows partition is FAT32. I ran disk utility and it found problems on the windows partition. It took two runs of disk utility repair disk to correct the problems. I also ran it on the OS X partition and it was OK.

When I booted back to windows, a DOS screen came up and it ran some kind of disk check/repair. When I opened ATITools it told me it had crashed (or something like that) after finding a max core of 602.10.

I then ran the find max mem. It ran quite a bit faster than the find max core routine. I got to watch it crash. When it crashed, a brief ATI message came on the screen saying the video card was no longer responding. Two seconds later the whole system went down again.

Same exact repair story as the first time. When I got back to ATITools it had found a max mem of 598.50.

Just thought I'd post this in case ATITools crashes/corrupts anyone else's machine.

As long as I'm posting. 3DMark05 seems to be a popular benchmark. With my 400/400 default I get 3853. Running at 460/470 (the authors recommendation for my machine) I get 4404. The highest I've tried so far is 500/500 where I get 4686.
John M. (Jmac) "

(added 4/25/2006)
" I've an intel 1.83GHz core duo 17" iMac with 1.5 GB of RAM.
The overclock (450/450) under XP don't produce good results: it works till I launch demos (www.pouet.net).
I've tested only two: deities by mfx and Then after 30 seconds the mac crash and I've to switch it off to rerun XP (with the usual scandisk process).

I've overclocked again at 400/400 (original at 310 / 310) and phelios Kaijen stopped after 1/2h of play (this is a 2D game). I find strange that we can't read the probes to know a bit more about temps and rpm.

I found also quite annoying not to know what are the maximum temperatures for GPU / CPU / HD.

I've an usb hub self powered connected to the mac and a printer (switched off), a logitech corded optical mouse, the apple keyboard, and an usb key connected to the mac.
Do they take current and does it makes things buggy? (they draw some current but not as much as a storage device that used only USB power. A powered Hub is a good idea if using a lot of devices or those that draw significant power-Mike)
I've redone the test twice with omega drivers latest rev and with the original apple (ATI) drivers.

I must also say that this brand new imac (3 months old) is working perfectly well under OS X but the display is always featuring artefacts under XP when used with all kind of ATI drivers whereas normal VGA driver don't produce any...
Thank you for your site, quite useful experience sharing.
-Emmanuel P. "

(added 4/25/2006)
"Thanks for the articles about mac overclocking. I have overclocked my x1600 (Imac 20", 2GB ram, 250 vram) with atitool. Using manual overclocking, the highest stable frequencies on my computer are 530 for the gpu and 630 for the vram. (630MHz?!?!?-Mike)
I have no benchmarks for these settings, but the 'fuzzy cube' in atitool is displayed at approx 130 fps. I have run Oblivion for hours with these setting without any artefacts appearing.
Any further increase in either the core or the memory frequency leads to artefacts for the atitool 3D-display. Needless to say, fan is running at max all the time, but the noiselevel is still lower than for an ordinary PC.
regards, Otto "

Notes on Battery Use: I was curious about any impact on battery runtime, this MacBook Pro owner mentioned some problems running on battery with his overclocked GPU:

(added 4/21/2006)
" I've managed to get my x1600 in my MacBook Pro up to 450/450 (I haven't tried anything higher as I'm perfectly happy with this) and played Doom 3 on high settings at native resolution with 2x antialias without any crashes. Gameplay looks great, but the "loading" screen seems to get some artifacts, oddly enough. I don't know why the loading screen would show artifacts and not the game, but I'm sure someone has an idea.

Another thing to note: my MBP does not like running the overclocked GPU off of battery power. I accidentally tried this yesterday, receiving repeated crashes for anything over 350/350 until I plugged it in.
-Aaron "

Anyone else run their GPU OC'd system on battery power and see this?

(added 4/21/2006)
" I saw the comments about how hot MBPs get playing games, and I'd like to mention that a PMU reset cools them off quite a lot. Playing Oblivion used to make my MBP too hot to touch in about 45 minutes of use, with stock clocks on everything. After the PMU reset it never even gets to uncomfortably warm no matter how long I play, or even with the GPU overclocked to 450.

To do the reset, shut down, detach the power cord and remove the battery. Hold the power button down for more than 5 seconds. Then reboot, and your MBP should be running much cooler.
-Stephen D. "

Odd... Anyone else notice this?

(added 4/21/2006)
" Mike, I'm the one the other guy quoted in your first message. (in the post by "Jmac" on April 7th above-Mike)
I used atitool and it allowed me to overclock to something like 540/596 on my 20" iMac with 256MB vram. I reduced the clock to 515/575 just to be on the safe side.

(The stock iMac X1600 clocks were 400/400 originally correct? (per jmac's post). Have you seen a significant benefit in games for instance? If you see any problems later (graphics glitches, overheating, etc.) let me know.-Mike)
Yes, the stock speed on the chip on the 20" is 400/400. Someone told me the stock on the 17" was more like 300/300. I don't have the aquarium screen saver, but I'll see if i can find it. Thus far I've not had any heat/graphics issues yet but I haven't tried playing any games except for Knights of the Old Republic. It played well without upclocking and still plays well with it clocked.
-Ken "

I don't know about ATItool (don't own an intel mac) but some PC GPU OC'ing features I thought had an option where it could be set to boost speeds when gaming for instance but throttle back when idle. (Nvidia's coolbits feature also has thermal monitoring, where it will force a downclock if the GPU temp reaches a certain point - for instance with a 6800GT (AGP card), the temp. threshold was 120C. (132C for the 6800 Ultra IIRC) **Update - see post above on ATI Tray Utils with Dynamic OC feature.

(added 4/21/2006)
" Hi Mike, My iMac (2.0GHz, 256MB VRAM) seems to top out at 513 core frequency, and somewhere between 440 and 450 memory speed.
I ran it tonight at 500/440 for 6 hours playing WoW -- seems quite stable, and fast.
cheers, Michael"

(added 4/21/2006)
" It scares me to read what people are doing to the graphics GPU & memory inside these MacBook Pro's, overclocking them by such an amount. I'm an avid overclocker myself (my G4 Digital Audio is clocked from dual 1.0 to dual 1.4 but I have also got another case fan in the top), but not with portables, especially ones that run as hot as the MacBook Pro. My dual core 2.0ghz runs very hot.
I've been playing Call of Duty & Far Cry on it both under Windows/BootCamp and running either of those games for more than a couple of minutes with most of the effects turned on and at playable framerate and pretty high res causes the system fan to come on. My machine is standard with a 5400rpm HD and I'm using it in about 18°C room, so anybody with a 2.1ghz & 7200rpm drive in a high ambient temp is IMHO asking for trouble.

Just my opinion of course, but people should think twice if they are prepared to buy a new logic board in the event they fry something. I'd be heartbroken if I fried mine.
Regards, Mick B. "

Only time will tell but you shouldn't overclock anything unless you're willing to accept the risk of a failure (either short-term or long-term). After all the complaints on MacBook Pro heat (w/no overclocking) I wondered about OC'ing the GPU (which of course increases heat). Apple may have downclocked the graphics for thermal reasons and I wonder about the widely varying reports on speeds (esp. vram speeds) - i.e. are all MacBook Pro's using the same spec X1600. Although you're likely to see image problems, freezes, etc. (forcing a downclock) before damage is done, nobody can guarantee anything. I created this page to track experiences from those that were willing to take the risk and to report on any problems seen (short or long term).
As I mentioned above, I have an OC'd 6800GT AGP card in a homebrew AMD 64 tower system and the card runs for hours in Doom3 w/o any glitches, but running that 3D Aquarium app for 5 minutes or so causes the entire system to reboot. (At first I suspected a PS or CPU issue, but it has a 470+W Pwr Supply with dual 12v rails, tons of cooling fans, etc. and it does it even with the CPU at stock/rated speed.) No damage done, but I thought it interesting that the Aquarium app put more stress on the system than hours of playing Doom3...

(added 4/20/2006)
" I guess I'm unlucky with my W8613 MacBook Pro. I can overclock the GPU to 450 without problems but my memory only works up to 333, nowhere near the 450+ memory some people are reporting.
-Stephen D. "

(added 4/20/2006)
" I have a MacBook Pro 2.16 GHz / 2GB Ram / 7200rpm 100gb HD and recently I managed to overclock the video card to 475 MHz on the Core, and 465MHz on the Memory, while maintaining Boot Camp's default graphic drivers. Anything above that and the machine's screen will turn black, forcing a hard reboot.

Now with these new settings, I get around 4350 points in 3DMark05. To compare, my 2.3GHz Athlon 64 with a Geforce 6800 (380Mhz/850Mhz) obtains a 4100.
Thanks, Marcos C. "

(added 4/20/2006)
" Hi Mike,
I've overclocked my MBP 2.0GHz's X1600 in Windows XP with ATITool 0.25 Beta 14. (download here). It can up to 460 / 360 and run several times 3DMark 05 without any problems. Sometimes when I am running the cube test (I don't know how to mention it, but there is a 3D test in ATITool with a Cube) and change the memory frequecy may crash the system. But most time the VPU recovery fuction saved me.

Acutally it is a quite strange overclocking experience to me , because on most desktop graphics cards, it may get glitch on the screen if you push the card too much before the system crashes. However on my MBP's X1600, it will run perfectly without any glitch at 460 / 360, but when I set it to 470 / 370, the system became very unstable and crashes.

I recommand people that have overclocking problems on MBP try overclocking the CORE first, because the core freq can be pushed a lot higher than the mem freq.
(I mentioned the much higher memory clocks reported by others, and ask if they were reporting clock rate or effective DDR rate-Mike)
ATITools does not report the DDR rate, so I believe they're reporting the real clock rate. and I have no idea how they can clock to such high speed. I can do a test today, maybe for 1-2 hours to see how stable it is.
-K. Cheung "

And remember "YMMV".

(added 4/20/2006)
" Just thought i'd let you know my MacBook Pro 2.16GHz is stable at 475/540. I haven't heard of anyone reaching higher and a friend who ordered his at the same time maxes out at 430/520. The overclock makes a huge difference in the latest games since everything appears to be GPU bound for now...these duo's are really powerful!

I'd be interested to know what the average overclock for the MBP is and whether i got a lucky unit or not...i have a replacement on the way for a few dead pixels but if it can't clock very high i might well keep this one. Let me know if you'd like more specific info on anything. GREAT site, i use it every day!
regards, Ant "

Thanks, and thanks for taking the time to send this.
I asked them both if they noticed any increase in heat or any problems with 3d gaming for long periods of time at the higher clock rates. (It's so frustrating to not have one of these right now - but later this year I'm going to try and get one myself.)

" Interestingly, the heat isn't very different. (i'm quite familiar with overclocking as i used to hardware mod my 1.5GHz G4 to 1.83 - PBAluminium). The graphics fan doesn't even run constantly, it comes on during periods of intense activity in quake iv and fear, but shuts down again almost immediately, nothing like the old aluminium's that spool down for ages.
The max operating temperature doesn't feel much different (unfortunately no hardware monitoring tools work at the moment), but i'd guess that during gaming the average top surface temp near the graphics chip is slightly higher. Nothing alarming really. Even after several hours gaming i've had no problems, pushing my core much higher causes VPU recover to activate or just crashes the machine, the memory produces artifacts at 560.
Despite many hours of tweaking and pushing the card past its limits it always recovers just fine and doesn't display any signs of a poorly overclocked system. I know this voids the warranty but from what i understand, no permanent change is made to chip settings in ROM? so apple can't deny you repair.

To be frank, the MBP isn't really up to playing the latest titles without modding the clock. Quake IV and Fear are transformed from choppy to fluid 60fps constant. (I'm very picky about frame rates, and need to be +40 the whole time to enjoy a fps type game). Having said that Half Life 2 runs great with or without the overclock at max everything and native resolution (once clocked you can run 2-4x anti-aliasing and 8X Anisotropic Filtering, looks beautiful!). I now run Quake4 at native resolution, high settings with no AA, everything on except shadows...frame rates almost always 60, never below 40.

The only benchmark i've done so far apart from fear is 3dmark 05, graphics score with the demo is approx 4491. Interestingly, the CPU score lags significantly compared to pc laptops with intel duo's at 2ghz. Comparing on the futuremark site i found my cpu score lagging by at least 1000 to the 2ghz pc's. I don't see how this can be improved by future drivers??? Is cpu performance affected by anything but the os?

I love this machine and i really hope you can get one soon, since i started using mac's 15 years ago this is the first time i've felt such a jump in hardware capability can be had for so little (well i wouldn't call it little, but comparatively speaking...) The machine is damn fast. If you're lucky when you get round to purchasing apple will have upgraded the graphics card and i hate to admit it but it could really do with a more powerful one. Let me know if you'd like any more scores/observations etc.
best regards, Ant."

(added 4/20/2006)
" Using ATITool 0.25 Beta 14, I could overclock both the core and the memory to 440. Clocking higher - to 470/470 made the system crash after 5 minutes of gaming, showing a black screen. I think I can get higher values when testing longer, but I'm at work now ;)

Just played BattleField 2 - Special Forces:
Display: 1152x865 60MHz,
Global settings: High
AA: 4x
After 30 minutes I quit the game (as I said, I'm at work), but it looks good, no glitches and not that much sound from the vents.
I'm on a MBP 1.83GHz with 1.5GB RAM
All the best, Jeroen "

(added 4/20/2006)
" I overclocked my 2.0GHz MBP's GPU to 470/450, I actually got it up to 484/490 and ATItool told me there were no artifacts, but then I tried playing world of warcraft on full settings and it froze. I systematically turned down the overclock until I could play WOW and Guild Wars on full settings indefinitely with no freezes. With the stable settings I got about 15 fps jump in WOW performance. (I asked to confirm what the "stable settings were-Mike)
Yes it is stable at 470/450. I was not very articulate before because I was in a hurry, but what I was attempting to say is the highest I could clock the gpu without ATItool telling there were artifacts was 484/490. However, when I went to play games to test out the new settings it crashed multiple times. In light of this, I decided it would be a good idea to turn the clock's down until I could play games stably; I had to go down to 470/450 before it was stable in game.
What also may be of interest is, after the crashes I could not connect to wireless networks. I had to leave the computer off for a few hours then run disk utility to get everything working again.

I was wondering is there a way to make the settings permanent because I have to increase the clock everytime I restart windows?
-Austin M/ "

See the "Auto Overclock on booting" section at this page.

If you've overclocked your Mac's X1600 (either iMac or Macbook Pro), let me know your results. Thanks.
BTW - The author of the french page at spacetitox.info wrote he's posted an English version (not his native language but better than the babelfish translation) He lists running 450/459 and includes some PC benchmarks vs a 318/300 clock rate.

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