Troubleshooting G5 CPUs

Zeke D

macrumors 65816
Original poster
Nov 18, 2011
1,006
156
Arizona
Many of you know I am having trouble with my G5. I want to rule out the CPUs. What will happen if I put a pair of 1.8Ghz CPUs in there? I know the 2.0 runs at 1000Mhz, and the 1.8s run at 900Mhz FSB. Will the 1.8s still work , lowering the FSB of the system to 900Mhz? or will it just fry my logic board?
 

Mengele

macrumors member
Aug 6, 2012
66
0
What will happen if I put a pair of 1.8Ghz CPUs in there?
It won't boot. G5 logicboards are CPU specific. Even just switching the existing CPUs A-B B-A will cause the cooling system to run at full speed all the time.
 

bengi

macrumors regular
Jul 21, 2011
112
4
It won't boot. G5 logicboards are CPU specific. Even just switching the existing CPUs A-B B-A will cause the cooling system to run at full speed all the time.
that's true because you then need to recalibrate the sensors. there's a specific software, which is a nightmare (it works 1 out of 5 CPUs).

however the question is still valid, wht are PowerMac G5 logic boards considered CPU specific?

Ben
 

havokalien

macrumors 6502a
Apr 27, 2006
650
49
Kelso, Wa
CPU motherboard

The bus speed is set and is half the speed of the CPU. A faster CPU may work but not usually, and will not boot the other way. The ASD ( apple support disk ). 2.5.8 for 1.6 to dual 2.0.

Good luck