Odd Hardware Issue MDD G4 - DVI No Video

[Camster367]

I've been having issues with DVI output on an MDD Single 1.0Ghz Geforce 4MX system that I picked up recently. The machine boots up properly, but just doesn't ever output anything to the display. When trying with graphics cards with VGA outputs, the machine works flawlessly over VGA but never DVI.

The closest I've gotten is using an AGP ATI Card, where I am able to get some badly distorted video out of the DVI connector, but again flawless video out of the VGA connector (this card is known working in another system). When using a PCI R128 in the system alongside the 4MX, I am able to verify in the system profiler that the 4MX card is detected, but I am never able to get video out of it.

Additionally, another 4MX from a quicksilver machine I also have will not output video in this system.

Any thoughts?

EDIT:

I have also tried another power supply, but the problem presents exactly the same. No way of verifying either power supply is valid at the moment, but I should have a new battery for my multimeter soon.

Secondary edit:

I actually just remembered I was able to successfully install OSX 10.5 via DVI on one of the other ATI cards I have, so maybe there is some kind of brand problem going on here? The 4MX out of this system won't work in any other machine either but I am not sure if that's a firmware thing or if it points toward the graphics card being bad.

 

[for this]

Two different brands of cards, same problem...
I would check the monitor's DVI port and the DVI cable.

 

[Certificate of Excellence]

My thoughts exactly. If you know the video cards DVI port functions correctly in other powermacs & vga works ok in the MDD in question, I suspect the dvi cable & or monitor port & would visually inspect for bent pins, lint etc. If the ports look ok, I’d swap in a different cable.

 

[Camster367]

I had the same thought regarding the monitor / cable, however the monitor works with other machines and the problem with output persists over multiple monitors. The display I've been using is an apple cinema display that I use with my G5, and it works with a few other G4s (and with that ATI card, as long as it's in another machine). I have also verified that I get no video out of the MDD on my Dell DVI monitor.

 

[Camster367]

Conclusion:

Turns out I was perhaps misremembering that the 4MX from the QS couldn't work in this system, because when trying it today it worked just fine. Looks like I've got a bad GPU with the original 4MX from this MDD. I appreciate the help, thanks!