Antec 900 psu problem! PLEASE HELP!

So i recently got a antec 900 case for free.
I had my xfx geforce 8200 motherboard with a Dynex 400 watt (the 50 dollar psu in Best buy) in a old stock eMachines case, and everything worked fine.

Moved all of it over to my New Antec 900 case and nothing, no activity. The red and green lights were on the motherboard but when i pushed the power button, nothing.

Just to see if it was my psu, got a 350 watt dell stock psu and its powered my PC up.
Presuming that my PSU was fried, i went a bought a brand new version of the DYNEX 400 watt i had, hooked it up...and nothing.

What is my problem? Because im out of ideas.

and now i put everything back to the way it was before i got the antec 900 case and nothing. No activity. Even with the new 400 watt psu.

Motherboard problem?

Stay away from that brand of PSU's , buy a Corsair 400W much better.

It's alright. It's in the Homebuilt Section.

You may want to disassemble the computer and breadboard the thing. It's a great way to test parts before you install in a case.

I have three Antec 900's. One thing you need, if you do not yet have it, is a case speaker - especially since you have a nonbooting computer.

I like the Antec case - great cooling. But the cable management ... Sigh.

I'm not fanatical about it, but I have found that cutting three holes in the motherboard tray really helps. Here's what I did:
http://www.tomshardware.co.uk/foru [...] _10_0.html