The PowerForce G3 ZIF 400MHz upgrade I received contained a IBM 400MHz PowerPC 750 CPU (aka G3) and 1 MB of backside cache (two 5ns IBM chips). The card was completely reliable even at 433MHz speeds. Quality of workmanship was good, with no sign of reworks on the board that would indicate a design mod after the printed wiring board was made.

Speed Settings:

The single rotary switch has settings from 300 to 533MHz. The card arrived set to position 3 which was 400MHz. I was able to run 433MHz reliably and others have reported 466MHz speeds were reliable in their systems but apparently not this one. At 466MHz the G3 would not boot, even with the cache set to 2:1. Maximum reliable setting was 433/288 with a 66MHz bus. Just a reminder - if you've set your G3 to run 83MHz bus speeds remember to set it back to the default 66MHz setting. The manual is written assuming the stock bus speed, so the default setting of 3 (400MHz, 6X ratio with 66MHz bus) will not boot if you have the bus speed set to 83MHz.

The photo below shows ratio adjustment knob which sets the CPU speed. No removing of the stock jumper block is required.

The compatibility issue with Retrospect backup software seen in the PowerForce G3 CPU cards for older Macs is not present in the ZIF model. I was able to complete a full backup of the G3 with the card set at 433MHz without errors. I've not had a chance to test it with the Adaptec SCSI cards but I don't expect a problem. I will be testing it shortly with a Adaptec Ultra 2 SCSI based 2940U2W card in both U2 and Ultra SCSI modes with wide drives.

The PowerForce G3 ZIF is compatible with the Apple G3 and All-In-One (AIO) Macs. It is not compatible with the iMac, which has a different CPU card design.

The hardware design was simple, reliable and fast. With no apparent compatibility issues seen so far, I rated the hardware features/design a 9.

The next page contains a summary and final comments on the product.