My computer has been running Windows and Linux perfectly fine with my 9800GT for the past year or so, but today it refused to boot.

When I press the power button, this is what happens:

1. Power button flashes once.
2. Fans whir.
3. Graphics card makes clicking noise.
4. Computer reboots.
5. Go back to 1.

The cycle just keeps going, and I have to yank the cord to make the computer stop. After about 30 attempts at booting it, the computer powers on and everything works.

I'm pretty sure that the graphics card isn't malfunctioning, as I've been GPU computing on it for a while now without any hiccups. But the strange thing is, the computer boots perfectly fine in only 5 boots if I remove the card.

The computer is a HP Pavilion a6028x Desktop PC:

• Processor: AMD Athlon 64 X2 (W) 4600+ 2.4 GHz (AM2 socket)
• Motherboard: ECS MCP61PM-HM (Nettle 1)
• RAM: 3GB DDR2 (two different brands)
• More specs here

Does anybody know what could be the problem? Any help or information would be greatly appreciated!