Is my PCI-e port or gfx card dead?

[SweetBearCub]

A couple days ago, my PC was running normally, just had its standard background apps open, plus a music player an my web browser, and I opened Steam to buy a game. Found the game, bought it, and just as I was finishing the process (not actually playing the game yet), I got a message that Windows Explorer had crashed, and then one that it was restarting, which happened over and over. The taskbar appeared and disappeared with each iteration. I timed it and managed to close my web browser and quickly bring up a CMD prompt, where I shut the system down with 'shutdown /s/f'.

After the system powered off, I waited a moment, and powered it back up. My keyboard LEDs flashed a couple of times, as normal, but I got no video output, and in its place, a beep code, 1 long and 2 short. I looked up the codes, and this indicated a video card failure.

I called a friend, since I had no spare video card, and I'm not so hot working inside my PC. He brought over a spare card, and after some diagnosis together, we determined that the PCI-e port closest to the processor was shot, as the system would not boot and would only give the 1 long and 2 short beep code with either my gfx card or the spare installed in it. We moved on to the next PCI-e port, normally unused. In that slot, the system still gave a beep code when my gfx card was installed, but it did boot and run normally with the spare card installed in that slot.

Is my PCI-e slot dead? Is the gfx card dead? Do I need to replace the motherboard and/or gfx card or other components? My system specs and a typical screenshot from CPUID Hardware Monitor Pro follow below.

MSI P7N SLI-FI, Mushkin Enhanced 580W P/S (HP-580AP), Intel Core 2 Quad Q6600 @ 2.40 Ghz (G0), 8 GB DDR2/800 memory, EVGA/Nvidia 9800GT (failed? Temp card is an Nvidia GT520), 3 hard drives 320 GB (system/apps), 1 TB (data), 2 TB (backs up the other 2 weekly), Windows 7 SP1 Ultimate x64

Nothing overclocked.

How are the power supply voltages? The screenshot is showing 2 days and 3 hours of data.

 

[SweetBearCub]

Update - After running an Nvidia GT520 for a while, I got a Radeon HD 7750 fro Newegg. Installed it into one of the x8 slots on my board (it has 2 x8 slots, and 1 x16 slot, the one which the 9800GT suicided in), and it worked fine. Even a slight increase in performance over my dead 9800GT. The shocker though is that while a friend was over one night, he suggested that I try the x16 slot again - The one that my 9800GT was in when it died (and recall from my OP that it wouldn't work in an x8 slot after that either) and the same one that the GT520 also refused to work in.

Not expecting much, I powered down the system, moved the card over, screwed it down, plugged in the monitor cable, turned my PSU back on, hit the power button... The LEDs on my keyboard flashed... One beep, then another.. Then my BIOS POST screen appeared. (!)

How the heck can that port work after a 9800GT died in it, and a GT520 refused to work in it, but worked in an x8 slot?

Incidentally, it appears that going from an x8 to an x16 slot provides no performance increase whatsoever. My benchmarks scores were unchanged. The only thing I can think of is that GPU-Z reminds me that my PCI-E slots are only v1.1.

Yay! No more forced upgrade of a supposedly slowly dying computer when I can ill afford it. If the GT520 could handle my gaming needs - Star Trek Online, World of Warcraft, SimCity 4, Sims 3, some old (Win9x era) games, I'd RMA the 7750, but alas it cannot.

Hopefully this machine will keep chugging along until DDR4 memory reaches the general consumer market, which is my target time for a new system, likely AMD-based for price/performance curve reasons.