First Look: Powerlogix's Z-Force!
Published: 10/25/99
Updated 11/29/99 for System Bus Speed Tests
[Update - Later today I was told the
Z-Force card I just tested was a prototype of a new mod, not the final
shipping version. Sorry for any confusion this may have caused,
as I originally was told this would be the final shipping version]
Bus Speed Tests:
Since the performance of any ZIF socket card will vary depending on the CPU module installed, one of the prime tests in my opinion of this type of card is how fast a bus speed the card will run. This shows how well the card is designed and for pre-Apple G3 Macs, bus speed is a direct factor in potential CPU speeds possible. (This has been covered many times in my past CPU Upgrade reviews but I'll rehash it here.) For instance with most G3 CPUs which have a 8X maximum Bus to CPU multiplier, the maximum CPU speed possible is 8 times the bus speed. With the more expensive 10X G3 CPUs, speeds of up to 10 times the bus speed are possible. As of this date, the fastest generally available G3 CPUs are rated at 500MHz, but hopefully soon we'll see 600MHz models available early next year.
Keep in mind that CPU speed, not bus speed is the primary factor in real-world applications performance. However as noted bus speed is an important factor when using the fastest CPUs available now (and in the future). With the fastest currently available G3 CPU (500MHz model with 10X bus/cpu ratio), only a 50MHz bus speed is needed to run that speed, however as faster rated CPUs become available,unless some
Note that even if your Mac is lucky enough to run a 60MHz bus speed (rare in the past), a 10x ratio G3 CPU chip would be required to run 600MHz (with an 8X ratio G3 CPU, the max speed would be 480MHz).
I tested the most recent Z-Force card that arrived on Friday afternoon (which had a mod not present on the original card sent last month) for maximum reliable bus speeds in the following 3 Mac models (each selected for a specific reason from the many other test systems here):
- PowerCenter Pro: Since this system was designed to run a 60MHz bus with the original 604e CPU, it's been a good test of maximum bus speeds with many past G3 cards. Although it does not support interleaved RAM (which hurts performance in some applications) its always been one of my favorite systems. As is recommended with all G3 upgrades now, I removed the stock L2 cache dimm before installing the new CPU card. This system has 128MB of RAM and runs OS 8.1.
- Genesis: This machine has a 9500 design motherboard with 512K of soldered-in L2 cache and has typically been very picky about bus speeds over 50MHz. With almost all PCI slots full, 512MB of interleaved RAM (all matched pairs) and internal 4-drive RAID array, it's one of my favorite Macs of all time. I've recently added a Formac Proformance 3 video card to replace the aging Ult. Rez I had originally used.
- 9600/350 (Mach 5 system): This cache-less motherboard (aka Kansas) has a 3.3volt design that has at times been a problem for some CPU card designs. It's also one of the few mac models with G3 clean ROMs. This system has 320MB of interleaved RAM (the stock pair of 16MB EDO dimms and matched sets of 64MB FPM dimms) and was recently updated to OS 9.
How I tested:
As mentioned in many of my CPU reviews, when I'm testing for max bus speeds I make sure I'm always running the CPU and backside cache below the rated speeds, so that any problem I see is related to bus speed only. I used an XLR8 G3 500/250 10X CPU ZIF module for these tests. To ensure the CPU/cache was not being overclocked, I made sure the ZIF card was set to a 8X ratio and the software cache controls were set to a 5:2 cache ratio. Therefore even at 60MHz bus speeds (the max possible with the Z-Force card), the CPU and cache would still be running below their rated speed and any any problems seen would be a direct indicator of bus speed limits of the base card/system combo.
To make a long story short the table below shows the maximum reliable bus speeds with the Z-force (based on several hours of stress testing, not my normal 1 week or review testing) and also a comparison to what speed the other ZIF socketed CPU card I've tested (XLR8 CarrierZIF) obtained in the same system. Retests were done with the CarrierZIF in these systems to answer questions by readers and since I had not explored maximum bus speeds with that card since the first revision sample from last summer (MAChCarrier G3/450 and G3/500 reviews used the 10X ratio CPU and tests were done for max CPU speed, not bus speeds in those reviews).
Max Bus Speed Results
|
System
|
Z-Force
|
CarrierZIF
|
PowerCenter
Pro
|
60MHz
|
60MHz
|
Genesis
(9500 mb)
|
60MHz
|
60MHz
|
|
9600/350
|
52.5MHz
|
55MHz
|
CarrierZIF Retest Notes: I retested the Genesis with the lastest revision CarrierZIF card (a MAChCarrier G3/500) over the weekend.
The first revision of the CarrierZIF only ran 55MHz max bus speeds in the Genesis & 9600/350 system with interleaved RAM. Although the CarrierZIF allows bus speeds of up to 66MHz, I did not attempt higher than 60MHz speed settings due to the limited time available for testing. 60MHz bus speeds booted and ran for awhile in the 9600/350 but eventually the finder quit. I did not test speeds between 55 and 60MHz yet.
Summary:
Based on the results I saw, the CarrierZIF now has some real competition from the smaller, lower-cost ($149) Z-force card from Powerlogix. It's possible there may be other improvements to the Z-Force card final shipping design and as is true with any CPU upgrade, your results may vary from mine depending on your installed RAM, motherboard revision and other installed hardware.
Z-Force Speed Settings:
The Z-Force has the following bus speed settings:
40, 42.5, 45, 46.6, 50, 52,5, 55 and 60 MHz
[Note - these settings were based on their current PF G3 manual, Powerlogix says the final Z-Force manual will document 66MHz and possibly higher
speeds]
The speed adjustment switch also allows setting ratios of 4:1 to 8x (applicable to all G3s) and also 10:1 (for use with 10X G3 CPUs only). The card's ratio switches are for use with OEM/Apple or other ZIFs without jumpers or switches for setting bus/cpu ratios.
The Z-Force is listed as compatible with the Following Mac models:
- Apple 7300,7500,7600,8500,8600, 9500 and 9600
- SuperMac/UMax S900 and J700
- PowerComputing Powerbase, PowerCurve, PowerWave, PowerTower/Pro and PowerCenter/Pro
BTW: The Z-Force to my knowledge is the only current ZIF socket card design that is PowerBase compatible (via a switch on the card). Powerlogix also noted that the card supports a 9X Ratio for G4 CPU use. Although not listed in the manual, based on my tests it's also compatible with the Daystar Genesis and Millennium models. For more info see Powerlogix's Z-Force page.
Availability:
The Z-Force should be shipping soon and has the lowest suggested list price of any ZIF socket upgrade card - $149 for the base card w/o CPU module at PL's web store.
I also noticed the Z-Force also has a 3-in 5 volt connector for a CPU cooling fan.
(Original 10/25/99 article follows)
Introduction:
Many readers (and I) have long awaited Powerlogix's ZIF-socketed CPU upgrade card originally announced earlier in the year. Well I'm very pleased to say the card does exist and should be available within a few weeks I'm told. The card just arrived today and I've not had time to test it yet but wanted to post some pictures of the card to whet your appetite.
The Z-Force is adjustable for bus speeds and CPU/Bus ratios of course with a small dip switch on the edge of the card as shown below.
Note how small the card is (not much larger than the ZIF CPU module). It's the same basic size as the latest Powerlogix CPU cards like their new low cost (under $170 usually) G3 250Mhz/512K model and G4 CPU upgrade card (see my First Look at PL's G4). This adds another player in the ZIF socketed CPU card upgrade market and I'm glad to hear the card will ship soon. Powerlogix's original suggested list price was $159, but I'll verify that price is still valid.
Note: For dozens of CPU Upgrade reviews and related articles, check the CPU Upgrades page. For over 2700 owner reports/ratings of CPU upgrades - search my Rate Your CPU Upgrade database (you can search for reports from owners of your mac model).
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