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7/31/01 Tuesday's News: Story DetailReturn to News Page


G4/733 Overclocking:
1 Clipped Resistor Sets 800MHz Speeds

Published 7/31/2001

Warning: As with any overclocking or hardware modifications, this will void your warranty and may not be reliable. You could also do other damage in the process. DO NOT attempt this unless you're willing to accept the risk of failure and expensive repair costs. The site publishers do not suggest you try this. This article is for entertainment purposes only and any information here is not guaranteed accurate. (Apple can change their module designs at any time, and they will not provide support for overclocked machines.)

A new Quicksilver G4/733 owner reported he used the Overclocking page linked last week here to run his machine at 800MHz. (The prev. G4/733->867MHz article shows the same info.) The 800MHz (6x ratio) setting is enabled by removing a single resistor (done by this reader by clipping/cutting the solder joints rather than unsoldering). He also commented on the noise factor with the new systems.
Of course remember this voids your warranty, may not be reliable and a 66.x MHz boost (less than 10%) isn't exactly going to be a night and day "seat of the pants" (noticeable) improvement.

" Ok, Mike...
Just wanted to let you know I successfully over clocked my new G4/733 Silver tower to 800Mhz last night. It was so incredibly easy, it was ridiculous. You've GOT to have good eyes, but the actual over-clocking couldn't have been easier if it had a dial :)

Here's the scoop. If you look closely at the directions and CPU speed choices on the Japanese page, you'll notice that the new 733 is the ONLY CPU that can be over clocked WITHOUT SOLDERING A RESISTER! In fact, 800Mhz is the only choice if you don't want to mess with soldering!

So, I took out an incredibly sharp razorblade, and simply cut the solder leads on each side of the resistor marked R3. This causes the transistor [resistor-Mike] to fall off the board, effectively setting the CPU for 800Mhz.
[Note: Actually an even easier way I have used is just to cut the one trace leading from the resistor, which is easier to undo (bridge it over with solder or conductive pen) and doesn't require removing the resistor.

Trace Cut Method for 800MHz Setting
(G4/733 Digital Audio CPU Module)

The image above shows a Digital Audio G4/733 example of the trace cut method. I have not seen a QS G4/733 to know if the PLL CFG resistors are the same layout/position.-Mike

One interesting thing to note about the new Quicksilver machines is THEY ARE LOUD! They have FOUR Fans! One for the CPU (thats new... it's rubberized and attached next to the massive G4 heat sink), [note - the Digital Audio G4s also have a cpu fan, at least on the Dual G4/533 and G4/733 models. I've not seen the 466 and single G4/533 to see if they do also.-Mike] One for the Case (same as before), One for the Power Supply, and One for my Geforce3!!!!!
[UPDATE: A different reader sent his Quicksilver Fan Noise Reduction Mods-Mike]

Anyway, I digress...
I bolted everything back up, prayed to the Gods of Computer Heaven, and hit the power button on my Cinema Display.
wait... wait... wait... "Chime"
:) Sweeeeet!

OS 9.2 boots... I see the desktop... everything looks great... but did it change the clock speed? I go to the Apple Menu, launch Apple System Profiler... and...
YES! 800Mhz!

So now, the only question is stability. I think it's working pretty good. (I haven't tried the Geforce3 yet.. still has the stock GeForce2MX card).

I played Quake3 (cg_drawFPS = 1 turns on FPS)... I saw an average of 30-60 fps at 1600x1200 with all options on. On 1024x768 (which I don't like because it stretches the image on my Cinema Display) it was 70-90fps, with an occasional 100+fps :) I played Quake3 for 2 hours, did some Bryce Rendering, etc... no lockups.

I've got a Sonnet RAID/66 card with a 160Gig Stripe set in the machine, and set to have file sharing on for the other Macs to access. They stayed connected all night long, and it didn't crash last night. So, that looks promising.

I'll need to test Photoshop on a big 200 meg file or so and see if that will kill it.
Also, I'm going to try and download a CPU temp. program and see if it is overheating.

But with all the fans, I don't think it will be :)
One note of interest...
On the Stripe pair, with the ATTO benchmark, at 733Mhz I was getting Read times of 110MB/s SUSTAINED at 512K sizes. Set to 800Mhz, I'm only getting 90MB/sec. Wonder why that slowed down?
[I also suggested Richard try ATTO tests with the 8MB I/O setting, since the 512K setting is well within the Hard Drive's cache size and is not a real indicator of sustained (to the platter) disk performance.
Also running any benchmarks or tests only after a clean reboot is best, since that assures the most consistent/repeatable system/ram/cache state for comparison purposes. -Mike

But so far, everything seems faster, the Bryce Rendering was faster, Quake3 & Unreal Tourney is faster (NEVER saw the fps hit triple digits at 733, it does every now and then at 800)... but hard disk access may be slowed just a tad. Wonder why?

Anyway, thats all... thought you'd like to know.

The cool thing is it was so easy... just slice the two solder leads on either side of the resistor, and *BOOM* an extra 67Mhz. No messy soldering, no ruining the CPU, just quick and easy... and most importantly... seemingly STABLE 800Mhz!

I think owners of 733's are lucky. No L3 cache speeds to worry about. Remember, if the CPU is fine being over clocked, but the L3 cache isn't, then BOOM, you still have a frozen sad Mac! :)
Richard H. Sales Engineer "

M. Isobe ran his 1MB L3 cache equipped G4/733 at 867MHz as noted in this article posted a few months ago. (Of course your mileage may vary). If you missed last Tuesday's news page, the Japanese site with the Quicksilver 1GHz overlock (from a G4/867) is here.

It may not help his fan noise problem, but last year I posted an article on how I reduced fan noise in a g4 tower (B&W G3 case is similar) that might help. It did for a G4 tower I had. For far more involved mods, see another Quicksilver owner's Fan Noise Reduction Mods.

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