Computer won't post new CPU installed

I just recently installed an X2 4400 into my computer to replace my 3700.
The first bootup it turned on without problem, I installed the MS and AMD hotfixes for dual cores. It would still restart fine, but after I shut it off for the first time it wouldn't turn back on. After playing for a while with the powerswitch on the MB and with the front panel power it turned on again. But the next day after shutting it off it doesn't want to start at all.

There is no beeps, none of the fans turn on, none of the Red LEDs turn on on the MB, no HD spin ups, nothing to indicate the power has been turned on. (There is an orange LED on the MB that glows as long as the powersupply is on) I've tried using the onboard switch on my DFI board to no avail. None of the components have given me problems before. The specs for my system are in my signature.

I made sure all the spacers for the MB and tray were in place and all the power connecters are plugged in.

Does anyone know a way to fix this? I was thinking of resetting the CMOS if I couldn't find a solution.

First off, this isn't the right place to ask for tech help. Try Hardware.

Second, you probably just bumped something loose while swapping parts. Try re-seating everything. Unplug and plugin power wires first, checking for obstructions, like dust bunnies. Then try the front connectors (don't switch them around, just unplug-plugin). Then work on components, like RAM, etc. Try not to remove the CPU unless it's absolutely necessary. You'll have to redo the thermal compound if you remove it, which may recquire ordering more if you don't have a ready supply.