Power Supply Problem

[Derp420]

When I install a new power supply in my computer, it turns on (fans spin, lights, etc.) but then turns off after 1-2 seconds. At first I figured it was due to the new power supply being faulty, but I've tried three of them now and I always have the same issue. I've tried with two Corsair TX650s and one TX550M. I don't think it's a problem with how I'm connecting things since I can put the stock PSU back in and have everything work.

This is the computer I'm trying to upgrade: http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=c03359045

I want to upgrade the power supply so I can use a Radeon HD6870 grphics card, though I haven't even tried installing that yet since I can't get the new PSU to work.

 

[alexoiu]

If you connect only the 24-pin connector from the PSU (no molex or HDD power cables), it does the same?

 

[Derp420]

Yes. With only the 24-pin, power stays on with the stock PSU, but Corsair turns on then off almost immediately.

 

[alexoiu]

That's weird. Could it be a customized board for a customized PSU?
You're not alone (see last posts) http://www.tomshardware.co.uk/forum/360736-15-need-advice-upgraded-graphics-card

 

[popatim]

How are you turning it on & off?
I ask because I've run into where theres an on/off switch on the back that it will turn on briefly and then turn right off but they've all worked fine when I leave the rear switch on and then press the power button on the front of the pc.

 

[Derp420]

I leave the switch on the power supply on. I use the power button to turn on the computer.