G5 Quad - Target voltage error - Replace processor

[Sepultura]

My G5 Quad has been collecting dust for years now. Last time I tinkered with it I got this and the computer would freeze. Red LED, loud fans, etc. I took the whole thing apart and it looked fine. Most users responded saying the logic board had failed. Some said it could be a processor.

A few months ago I borrowed a friends Intel Core 2 Duo which uses DDR2 ram. So I took all the ram from the G5 and tested it in the Core 2 with memtest86. I ran multiple tests and 2 sticks seemed OK after 14 hours of running them. I tried different slots with all the ram, but I am sure 2 are good and 2 are not because those ones got errors early on in the test. The ram is from OWC and is 4x2GB for a total of 8GB.

I put the 2 working sticks in the G5 today and I managed to boot the ASD CD! I ran the thermal calibration test and this is what I got after 30 seconds. I am now running the full 47 test. It's on ram and seems to be working.

 

[ziggy29]

Not sure if the suggested "fix" will help, but you never know. Could well be a processor issue.

I have to ask and I don't want to hijack -- did you get functional mouse control when you booted ASD? Were you able to get to Thermal Calibration using the mouse? When I boot this up on my Quad, I don't get a cursor and I don't know how to navigate to the Thermal Calibration menu item....

 

[Sepultura]

Not sure if the suggested "fix" will help, but you never know. Could well be a processor issue.

I have to ask and I don't want to hijack -- did you get functional mouse control when you booted ASD? Were you able to get to Thermal Calibration using the mouse? When I boot this up on my Quad, I don't get a cursor and I don't know how to navigate to the Thermal Calibration menu item....

What is the suggested fix?

Also yes I plugged in just a regular mouse. No keyboard.

I am still running the 47 stand alone tests. It's been going for 40 minutes and memory is just about to finish. CPU is next we will see what happens.

 

[ziggy29]

The suggested fix is what the calibration said -- "replace the processor". That said, if you are running with good RAM sticks, the system is stable and the temps aren't out of whack, maybe leave well enough alone?

I'll have to try to boot this without a keyboard attached. Thanks for the possible clue. The standalone tests may be of some use.

 

[Sepultura]

The suggested fix is what the calibration said -- "replace the processor". That said, if you are running with good RAM sticks, the system is stable and the temps aren't out of whack, maybe leave well enough alone?

I'll have to try to boot this without a keyboard attached. Thanks for the possible clue. The standalone tests may be of some use.

If it is the processor(s) I won't bother. I know with this model you can physically swap the cpus and disable one and run it as a dual core. I should have done that the first time I took it apart to see if that worked. Won't bother taking it apart again though, probably just sell the G5.

It's currently running the CPU Slewing verification test. Looks like it is frozen though. Been stuck at 41 minutes and I can no longer move the mouse. The bar hasn't moved either. Going to give it 10 more minutes.

 

[ziggy29]

Yeah. I have a CPU core that I just swapped out of my Quad where one CPU is almost on fire as soon as you start it up. I can't even get into Open Firmware to disable it some times. Fortunately I had another quad G5 with (I think) a crapped out PSU but a known good CPU core, so the swap gave me a good unit.

Learning something about the mouse. For one thing, as soon as I entered OF and typed in the command to boot the ASD, I pulled the USB connection from the keyboard and the mouse worked! I ran thermal calibration and got an error on CPU0 ("CPU Temp @ 25 out of spec") but CPU1 passed. And both have almost the same temps when I'm running and both are fine, so I'm confused. I'm not going to stress on it, because the temps are OK and the fans aren't racing.

When it's running stuff the cursor seems to freeze for 15-30 seconds at a time before it response to movement; at least that's what it did for me during the calibration.

 

[Sepultura]

Sounds like your CPU is OK. As long it's not blowing full speed like mine is I wouldn't worry.

Since I know the memory is good I unchecked those tests and unchecked the CPU tests which froze before. I ran the other 32 tests and it passed. So I am going to try the CPU by itself. If it doesn't work I guess it's toast.

 

[Sepultura]

I tried CPU 0 and 1 tests together and it froze. I left it for 10 minutes and there was no sign of progress. I tried CPU 0 by itself and CPU 1 by itself, still froze. So after all these years I am lost. The computer boots the ASD, the red LED stays on, and the fans blow loud as hell... Nothing freezes until I run the CPU tests. I have no hard drive for this system or I would try installing Leopard.

Just for another test I put the bad memory that failed in memtest86 back in the G5. In DIMM slots 0 and 1 the computer would not boot. It would beep twice and fans would go loud. I put it in DIMM 2 and 3 and it booted to ASD. I ran the memory tests until complete (37 minutes) and they passed. I still think this memory is bad though because it failed after many more tests in memtest86.

I think it's time to give up on this G5 and part it out.