Radeon 9800 burning power cable 3 times! *please help!*

[15th Warlock]

I have a problem with my 9800Pro@XT, it has to do with the molex thing where you plug the power cable.
The problem is, the power connector in my video card is burning all molex terminals I plug into it. The last time, even the white plastic from the molex turned brown, and I burned my fingers when I tried to unplug it.
The molex thing always burn at the red cable end (positive I guess :confused: ), and the 3 times, it happened after having my pc running for more than 2 days straight, and underclocking my vidcard to 300/300 (maybe this have something to do :confused: )
I see there's some kind of pattern, as first, my PSU died only two weeks after buying it, it was an Omega 450Wts PSU, and i got a new one after I RMA'd it.
Then, the fan speed regulator from my Tt Giant 3 VGA cooler burned out, I changed it for a new switch which I soldered to the old panel that came with my cooler. I even posted a thread about this here:

http://forums.techpowerup.com/showthread.php?t=709

Then, the splitter power cable that came with my card burned out too:

http://forums.techpowerup.com/showthread.php?t=1187

I connected my video card directly to the PSU, and it has burned out two more molex connectors since then. After it burns the connectors, I get the "power cable not connected to your Radeon 9800" message at boot.
I'm certain there's some kind of relation between all those events, maybe something isn't grounded right, after the second connector burned out, I disassambled my whole PC, down to the case, and rebuilt it again using a borrowed PSU, and then it burned a third connector! :(
Is there any explanation to this strange phenomenon? My electric conection is grounded, and i have all the necessary precautions to keep any voltage irregularities from reaching my PC.
Please, help me with this problem, I don't know what else to do! I must admit I have almost no electric engineering knowledge at all, I only know the basics, thank you all for your help, I appreciate it :)

[wazzledoozle]

Are you using volt mods?

[15th Warlock]

Are you using volt mods?

No, I haven't altered anything in my video card, apart from flashing it to an XT and changing the stock cooler.
Btw, may I add that I get no rendering artifacts whatsoever.

[Urlyin]

15th...

It sounds like the card is pulling more than it's fair share of juice... Do you have a digital volt meter to check the current it's drawing? You may want to flash back and check the voltage then as well ... I'm assuming that it's in the card obviously given you've tried several PSU. The card is pulling power from all three rails. Which sounds like it's on the 12v rail, 3v is coming from the AGP port and the 5v is on the molex with the 12v from what I understand. You might want to verify that you didn't add an extra post under the board that is grounding out ... I would suggest you not let it run without someone being there or overnight... you don't want to wake up to it flaming on, just my safety concern :)

[15th Warlock]

15th...

It sounds like the card is pulling more than it's fair share of juice... Do you have a digital volt meter to check the current it's drawing? You may want to flash back and check the voltage then as well ... I'm assuming that it's in the card obviously given you've tried several PSU. The card is pulling power from all three rails. Which sounds like it's on the 12v rail, 3v is coming from the AGP port and the 5v is on the molex with the 12v from what I understand. You might want to verify that you didn't add an extra post under the board that is grounding out ... I would suggest you not let it run without someone being there or overnight... you don't want to wake up to it flaming on, just my safety concern :)

Yes, you might be right, although I'm thinking that my case is the culprit, I think it is not properly grounded, because I noticed that my Tt fan control switch didn't work when it was in contact with the case, but it worked perfectly fine when I was holding it on my hand.
This morning I bought a new case with a plexiglass window and a new 450Wts PSU, I just installed everything and so far I haven't had any problems.
I will go to a hardware store this evening and buy a volt meter, how may I check my vidcard's voltage? I mean, the voltage for each power source? (AGP slot, molex and so on...) Thank you for pointing this thing out :)
Oh, I forgot to mention that a 40GBs HDD almost died too the last time my vidcard burned a power cable (lots of bad sectors and it takes a long time to boot), I got a replacement and reinstalled my OS.
I'm keeping my PC off when I'm not at home, and won't be using it overnight anymore, thank you guys for all your help, I'll keep you posted on any news :)

[C&C Freak 2K]

While we're [were] on the subject of grounding, check to see if your motherboard is mounted correctly.