Broken ports on Graphics Card? VERY wierd.

Hey. Usually I can find an answer to my problems by looking through forums. This is the first time I have had to use them.
SORRY for the long post. Its complicated.
Here is an introduction to my obscure pc:
About a year ago my power supply blew up and I couldn't afford a new one, so I used two old ones I had (1 wasn't enough power) and wired them together and got my computer working. I just have to press two switches to turn it on. Yes I know, and I'm getting a new psu in two weeks. Recently, My screen wouldn't turn on when I turned on the psus (after 6 months at least of no problems) but a few restarts fixed it.
Here is my problem:
I was playing oblivion with several (like 50) user-made mods. All worked fine, occasionally my pc would crash after half and hour to an hour of playing with a quick glimpse of a blue screen with white writing. could have been bsod, not too sure. But I figured its my cpu or ram getting overloaded cos I am using high res texture packs. A few days ago, I went into a shop that I hadn't entered before, and the screen got the purple textures and blocky trash everywhere (im used to seeing it) and the screen went completely red and then black. I could still walk around and hear me interacting with stuff. So i restarted and the screen wouldn't show anything. Eventually I heard the windows startup sound and the graphics card was hot like it was still working. Eventually, just for fun, I switched the monitor cord to the other DVI port. It worked. Now here's the funny part. I decided to try and break it again. So I loaded oblivion and went into the same save game and the same thing happened. Now I can't get a picture at all. (I am borrowing someone elses gfx card at the moment). I have tried everything. Even a seperate power supply for the card. BUT the card still gets hot and the pc still starts windows as if its working fine. It appears to me like it is the DVI ports on the card that got broken (who knows how software can do that). I still havn't tried the extra tv-out port cos I don't have a tv with component-in to use.
Help? I have tried everything I can think of EXCEPT putting my card in someone else's pc. (even took apart the card and cleaned the dust out.) I just don't have a spare pc with pci-e right now til next week sometime.
It has me totally stumped which is a first.
I have faith in you.
Thanks.

EDIT:
I tried putting my gfx card in my second pci slot (while using the borrowed one in the first) to see if I could diagnose the problem that way. I went into device manager and it said "Windows has stopped this device because it has reported problems. (Code 43)"
'Problems.' How specific. I don't know what 3rd party tools to use, and the ones I have tried don't see it. dxdiag doesn't see it either. This is a massive post. sorry again.

PC Specs:
AMD Athlon 3500+ 2.21Ghz
2GB Ram
GeForce 8800GTS 640mb