[Filmo]

My girlfriends computer is driving me crazy.

During operations, she got a that multi-languaged screen that dims the rest of the screen and says basically "You need to hold down the power button and restart the machine." ( I don't know the exact name of this 'screen', but I've seen it before)

At first I thought it was the hard drive as it was making weird noises. Long story short, I've got a new drive in the machine with 10.5.8 that is confirmed working on a different Dual G5 (runs like a champ on that machine).

I've run the hardware test, including the extensive memory test and everything passed with no defects.

I replaced the 3.6v battery

I reset the PMU button and the pram.

Blew out the dust. Moved the hard drive from the top to bottom slot and vice versa.

From cold start, it will boot and run for a bit then it goes to the freeze screen after a bit.

From immediate reboot after this happens, it won't boot at all.

If I let is sit for a few hours, it will again boot, but then freezes after a bit.

Seems like some sort of heat issue, but the fans all seem to be working correctly and during the hardware test, they were running 'full' the entire time, so I know all the fans 'work'. (They also make that correct G5 power up sound of spinning up fully for a few seconds when I boot)

Any thoughts? (because at this point I'm out of ideas.) Power supply?? (I don't know of anyway to easily test this.) Loose CPU heat sinks?? Just generally dead??

[reader50]

If you boot from the OS X Install DVD, how long does it run before you get the kernel panic screen?

What extra hardware is connected? PCI cards, USB devices, FW devices.

[Filmo]

Nothing else attached. USB mouse and Keyboard, no PCI cards or firewire.

Even tried pulling OUT the DVD drive and just booting with only the HD disk in the machine.

When I installed from the DVD drive (prior to pulling it), it froze at some point during the install. I tried two different DVD drives in the machine.

The install currently on the hard drive was built on a working G5, not from the faulty G5 in question.

I assume you mean put in the DVD disk and boot to the installer as as opposed to 'boot-dvd-to desktop' The 10.5.x installer disk we have only boots to Installer.

[osiris24x]

I've seen this issue many times over the years and every time it was a faulty CPU. You might try running TechTool Pro on it on loop mode 100 times or so. This was generally sufficient for me to recreate a kernel panic for the Apple store guys to see.

[Filmo]

I'll give TechTool a shot, but frankly if it is the problem, then the computer is a throw-away as I can buy a used working version on ebay for like $200 bucks, so why bother paying apple to fix it.

I guess I'm just trying to determine if I skipped something obvious or if it really seems like a hardware (CPU, Logicboard, power supply) issue. Any sort of hardware issue == into the recycle pile.

[reader50]

Symptoms suggest a hardware problem, such as power supply, CPU, or motherboard. Since it passes AHT, that suggests the motherboard is OK. And the first CPU is probably OK too, assuming AHT mostly runs a single thread.

There is one hope left - that it's the video card. Can you beg / borrow / steal another Mac video card for testing? AHT does not stress the GPU with composited graphics, whereas OS X does. Remove the original card while testing with the new one. The new one can be PCI or AGP.

[Big Mac]

If it's happening when booted from the install DVD it is some sort of hardware problem. Most of the things you tried would have no effect, like switching drive bays or blowing out dust.

The one thing I didn't see you mention is whether or not you thoroughly tested the RAM by testing only a pair at a time. Bad RAM could cause instability, although it's a stretch. It sounds more like a motherboard problem, unfortunately.