Dell Demension e521 Wont Boot

So what happens...
When you push the power button it lights up for a second then immediately shuts back off. My initial thought was that there was a power supply issue, but I've now scratched that as I've used a different power supply in the case, and received the same result. I also put the Dell Power supply in another case, which booted normally.

The Specs:
Amd 64 X2 series
2x512mb Some off brand I think.
Had a 7300gt in it, but it has intergrated graphics so I pulled that out.
Right now I'm looking around for similar problems and troubleshooting.

I await your knowledge.

D

Try running off of just one DIMM of memory ... or use known working memory from another rig. Also if you have another CPU that is compatable with the socket... swap that out and test it also.

If none of that works, then you have a defective Mobo. Which is most likely the case anyway. Because if the Mobo was healthy... you'd at least get some error beeps and the computer would keep running (not doing anything, but powered up at least).

Double check your cabling as well and make sure the power cables are connected in the right places. And of course double check the seating of your CPU and memory... but you did that already, right?