Alright, I need some advice. I have been building a budget build to replace my current PC. The build is:

AMD Athlon64 X2 3800+
ECS K8M890M AM2 Motherboard
2 x 1 GB OCZ ddr2-800 memory
eVGA 7900GT KO superclocked

Anyway, I just got the video card the other day and was finally able to set everything up. I put it in and used one of those 6 pin HDD power cables. The computer will turn on for a second then shut itself off. If I leave in the card, but remove the 6pin connector, the computer will turn on, but I cannot get a signal from the GPU (the card's fan will run though, so it is getting power).

As a test, I ran a 7600GT and it posted video no problem. My powersupply (though it isn't great), meets the minimum 20A 12V requirement (it's a 420 watter from Raidmax).

Is the card dead or am I just underestimating the power requirements?

I'm guessing it's a power issue. Do you have much else in the computer? Hard drives, CD drives, etc? One could probably look up the power requirements for the 7900GT I suppose, to make sure the amperage and wattage you have is good enough. Even with the amperage, if your PSU doesn't supply enough wattage it wouldn't work either.

Then again, I run my system (Below) with a 480W PSU.

At this point, 1 IDE HDD, 3 LED fans, CDRW, and floppy... I tried it without the LED fans and no change.

Bump for help, plz