Computer will not power on with graphics card installed

[vnf4ultra]

System specs:
AMD Athlon X2 3800+ Stock
MSI GeForce 6100/nForce 410 Mobo
1GB Kingston, 512MB Generic
Nvidia Pci-e 6600GT
WD 160GB SATA
HiPro 250W PSU
XP PRO

I have an odd situation with one of my computers. I was using it and everything was fine, but then I went to work on something else leaving the computer powered on, but not doing anything. When I came back, the computer was off. I pressed the power button, no response at all. No sounds, no lights, no fans...nothing.

I unplugged the computer for a bit and tried again, but still no response. I noticed that the power supply's "trickle power" led was off even when plugged into known good power (the led's always on if it's plugged in).

I figured it might be a failed PSU, so I opened the case. When I opened the case I distinctly smelled the "blue smoke" that burnt electronics make. I then connected a power supply tester to the 20pin connector. When connected, the PSU powered up and the tester showed correct voltages on all the rails.

I then reset the cmos and plugged the psu to power again, and tried to boot, with no response.

I stripped the machine down to a "bare system" (mobo, 1 stick ram, onboard vga, cpu, psu). To my surprise, it booted right up at this point reporting that no bootable drives were found, which is correct, no drives were connected. I then plugged in my usb keyboard and entered the bios. I reset the time and some other settings.

So then I tried connecting devices one at a time. It came down to the video card. If the video card is connected, the computer will not even attempt to power up. The video card heatsink was very clogged up with dust, so I cleaned it and took the heatsink off the gpu to see if the core looked burnt. The gpu looked normal to me however and the card has no smell of smoke. So removing the card "fixed" the problem, but I'm concerned that I smelled smoke, which didn't seem to have come from the "failed" component.

I have two theories besides just having a bad video card. First, I still suspect the power supply, after all it is a 250W HiPro. I'm thinking that maybe removing the card put less load on the power supply allowing the system to work without it. My second theory is that maybe part of the motherboard involving the pci-e slot fried.

I think my next plan of action is to try the graphics card on another "crap box" of mine to see if it works or not. I guess I'm just wondering if anyone has any other ideas or comments about it, or if anyone has had anything similar happen.

--
Cliffs (for those who won't read :wave


-System would not power on.
-Removing video card allows post and boot.
-Burnt smell in computer, but video card not burnt.
-Don't really think the real problem is video card.
-Theories on why removing card "fixes" computer.

Edit: Added Picture of 6600GT.



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[CCT]

Uninstall the PCI-E card drivers (this allows booting and switching to the card using VGA which is low power).

Does that work?

No?

Try another PCI-E card - if it works, your old one is toast.

If it doesn't, your PCI-E slot is toast.


Maybe.

 

[Tmagic650]

Because the GPU fan was clogged with dust regardless of not smelling smoke, when you take the card out, and the system boots, I would suspect that the video card is fried. Trying another card will confirm this

 

[vnf4ultra]

Uninstall the PCI-E card drivers (this allows booting and switching to the card using VGA which is low power).

Does that work?

No?

Try another PCI-E card - if it works, your old one is toast.

If it doesn't, your PCI-E slot is toast.


Maybe.

I'm not sure how I could uninstall drivers if the system will not power on. I will test whether the 6600gt works in one of my other computers. I think there's a pretty good chance that it will work and that the problem lies elsewhere.

I do notice that the northbridge on the system in question gets extremely hot. It has a small heatsink (no fan) installed on it. It is too hot to really touch for more than a fraction of a second. It feels hotter than my cpu heatsink when it's at 60C. This board doesn't seem to have a northbridge thermal sensor or else I'd check the temperature. I wonder if a northbridge could overheat and take out the pci-e bus as a consequence. I tested the system with the onboard graphics and it seems ok, I even ran orthos stress test and it didn't crash or lock up.

 

[Tmagic650]

"I will test whether the 6600gt works in one of my other computers. I think there's a pretty good chance that it will work and that the problem lies elsewhere"...

If this is the case, be prepared for installing a new motherboard. Drivers have nothing to do with this problem at this point

 

[Obi-Wan Jerkobi]

You might also want to try a different PCI-E video card on this mobo to see if CCT is correct.

 

[CCT]

You said: "I stripped the machine down to a "bare system" (mobo, 1 stick ram, onboard vga, cpu, psu). To my surprise, it booted"

I said: " Uninstall the PCI-E card drivers (this allows booting and switching to the card using VGA which is low power).

Does that work?"

You said: "I'm not sure how I could uninstall drivers if the system will not power on. I will test whether the 6600gt works in one of my other computers. I think there's a pretty good chance that it will work and that the problem lies elsewhere."

So, what the heck is it? Will it power on or not. I get cranky when people say this kind of stuff!

 

[Tmagic650]

"So, what the heck is it? Will it power on or not. I get cranky when people say this kind of stuff!"...

Good point CCT, I am still siding with a bad video card at this point. The motherboard being bad would be a real bummer indeed!

 

[vnf4ultra]

Problem Solved

The system will always power on if using onboard video (nVidia 6100) without the 6600GT installed, but will never turn on when the 6600GT is installed. Make sense?

Edit: I tried the 6600GT in my "backup rig." Holy ****, the card literally caught on fire inside the computer. The card instantly lit up in a bright orange glow of flame for a few seconds while I frantically cut off the mains. Luckily the computer seems alright with it's own video card installed again. I guess this solves the problem...the video card really was the culprit. It looks like the one MOSFET was the problem. At least it went out in a bright puff of glory.

I thought I'd post a pic of the burnt mosfet. I lent out my camera so I used a webcam, but you can still see the scorch marks.

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