Troubleshooting a PowerMac G5

[IvantheDugtrio]

I'm revisiting a G5 dual 2.5Ghz that I last worked on around 2015. Back then, I had already encountered some issues with the ATI X800 GPU having a missing pad at the edge of the AGP slot as well as checked on replacing the PRAM battery. I last recall replacing the X800 with a 9600 which got it to boot, after which I installed Debian Jessie and called it a day.

I go to check back on it now and it plays the chime but there's no video output, and after 5 minutes or so the fans ramp up to 100%. The system has been unplugged from the wall for years, sitting in a somewhat dusty garage. Is it possible the PRAM battery I replaced back in 2015 is completely drained and it needs another replacement, or if the ATI 9600 is now dead?

Conversely I have an iMac G5 next to it which holds up a lot better and has never had issues with booting up.

 

[AphoticD]

Testing the PRAM battery with a multimeter would be a first step - either 3.6V for the half-AA type or 3V for the coin battery type. Then I would try reseating RAM, AGP, PCI-X expansion slots and HDD SATA.

There is a CUDA reset battery on the board from memory; unplug power, wait 10 seconds, press reset button (once only), wait 15 seconds, plug power back in and power on.

If none of the above helps, I would next attempt to dismantle further to reseat the CPUs.

 

[AphoticD]

I should also mention my experience after having my G5 in storage for about 5 years, where I had the same symptom of chime ok, with no image and then fans ramping up. In my case my Radeon 9800 Special Mac Edition (256MB) Had failed and also fried the AGP slot. I was able to boot without a GPU (confirmed with screen sharing). Ultimately, I replaced the logic board and put in an Nvidia 6800 GT Ultra DDL which has been solid for the past 6 years.