Will not post, tried new mobo, ram and cpu.

Ok I HAD a working Athlon xp 2500+ system working using an ECS nu2400-a. Decited I would get a new CPU with 400 mhz fsb. Got the Athlon 3200+ xp. It is stated by the manufacturers web site that it is compatible. So I plugged it in, and it didn't POST, didn't beep, no LEDs lit on the front pannel. Put the old 2500+ back in, updated the bios. Booted fine. Put the 3200+ back in. Same results, nothing, fans turn though, hard drive spins, but nothing else. Put the old cpu back in. Does not work. I bought a new motherboard (ASRock K7upgrade 600), returned the original 3200+ cpu and got a different one, (the die? on the top of the cpu did not look good), bought new ram. Still the same problem. Ok so am I looking at a power supply problem? Since it was working before, could all of the....turning off and swapping CPUs killed it? That seems weak. After I gave up (1 hour ago) I opened up the power supply just to do a visual check, capacitors etc. Looks ok, I just dont want to drop $100 bucks on a PS (small town) and still be stuck. Ok ill stop before this turns into a book. Thanks for any constructive input.