Power problems

[Voxenn]

Hey guys, just wanted to ask a quick question. I've searched throught he forums already, and have read the stickies and such but couldn't find something to help me. I've tried the solutions that I thought might help, but they didn't work. I just recently purchased:
MSI K8N Neo V20
AMD Sempron 2800
Ultra X-Connect 500W power supply
ATI Radeon 9250 256MB AGP


I know that's a large power supply, I was originally going to get SLI parts but I got d***** around and pretty much had to settle with the stuff above. I've installed all the parts, everything is well fitted and properly connected but there is no power. The fans don't start up, there's absolutely no noise. *After* I disconnect the power cord from the PSU, there is a 1 second noise like it's powering up, it's just a slight squeaky noise. Any ideas on what could be the problem? I've even taken everything out of the case as one of the stickies had said, and tried to start it up with a screwdriver with just the bare minimums. That didn't work as well. Any and all help would be greatly appreciated.

[Alaron]

Do you have both the 20pin ATX power and the 2x2 square power hooked up? That can be a common mistake.

If both power connections are there, and it still wont boot out of the case, you'll have to substitute parts to track down the problem area. I would start with your power supply. Ultra units are low quality.

[DarkPacMan77]

everybody downs ultra psus, but if you have one that actually works, it most likely is one that will continue to work for a long time. There are actual loyal fans of ultra ( i would guess for price)

really sounds like you are missing the 2x2 power hook up though like alaron said

[Voxenn]

Ah ok. No, the 2 x 2 connector is in. I guess I should have done a little bit more research on the power supply, heh. I'll see if I can grab my roomies power supply to see if that's the problem. Thanks for the replies. :-)