Powermac G5 Quad Starts but no Video

[Mercedes33]

Hey
I have an serious issue with my Powermac G5 Quad. When i press the Start Button it turns on but no screen is there. Its all black. The Fans are at normal speed but when the Powermac is longer on the power the fans are spinning more and louder
Can anybody Help?

I tried to siwtch die graphicscrads . I have 2
And also the RAM moduls

Nothings happend

 

[Doq]

Check the lights on the inside. Perhaps your Quad is thermally bound and the CPUs are checkstopping.

 

[Mercedes33]

Thats the thing there is no light on. The Fans are just spinning normal until it turns to an airplane

 

[MisterKeeks]

Try switching the graphics card into a different PCIe slot, I have a Quad which will refuse to boot with anything in Slot 1.

 

[mac57mac57]

This could be a lot of things.

If the fans come on when you turn the machine on, all that means is that you have successfully applied power to the system. It doesn't seem like it is showing any signs of "intelligent" life (i.e. CPUs running). Further, you say something that suggests that the fans eventually "run away", ramping up to full speed. This also implies that there may not be any intelligent life in the machine.

You mentioned that you have tried changing the video card. Presumably the one you have, in the slot it was in, used to work, and now doesn't, or at least it is not producing any output. Since you have changed the video card to no good effect, and the fans eventually "run away" my guess is that you have a CPU-related fault. It could be as "simple" as a cooling failure, in which case the CPUs shut down, or it could be something deeper and harder to find, such as logic board failures, RAM failures, etc.

This is a tough one to debug and/or diagnose. You will just have to patiently walk through each possible failure scenario and try correcting what you can, one at a time. I am doing the same thing right now with a suddenly non-responsive old Pentium IV system. When a computer just stops working, figuring out which part (or parts - you may have multiple layers of failure happening) has failed can be REALLY frustrating!

 

[Doq]

Thats the thing there is no light on. The Fans are just spinning normal until it turns to an airplane

I should probably elaborate on this:

On the inside of the Late '05 G5s, including the Quad, there are a series of LEDs on the logic board on the front edge next to the upper deck of RAM.

Here's a table for what each LED indicates. If you have no lights, take off the air deflector (the big plastic piece) and take another look. If all of the LEDs match "expected condition", then at minimum your processors are alive and you can reasonably rule them out, at least for now.

 

[mac57mac57]

@Doq, this is GREAT information! I have been driving a late model 2005 PowerMac G5 since... well ... early 2006, and I have been blissfully unaware of this the entire time. I have to go crack open my Power Mac and feast my eyes on these LEDs! Thanks again.

 

[Doq]

@Doq, this is GREAT information! I have been driving a late model 2005 PowerMac G5 since... well ... early 2006, and I have been blissfully unaware of this the entire time. I have to go crack open my Power Mac and feast my eyes on these LEDs! Thanks again.

I'm shocked you weren't aware. The red checkstop light that briefly shines when turning on a Late '05 is bright enough to see through the front grill.