Boot Up Problem

I just recently took my computer apart and was giving it a good cleaning cause of all the dust. When I put everything back in and tried to boot up, I got nothing. Both my CDRW and my DVD drive seem to get power, all 3 of my HDs are spinning, all my fans are spinning, and the light on my mobo is on, but I am not getting anything on my boot up screen. I have gone back inside and tried rewiring but nothing seems to work. Anyone have an idea of what exactly could be wrong? Is my processor shot? Did I fry something? I tried my raedon in another computer and it works fine. I cant seem to what is causing it not to come up, i have never had a problem before.

MB ASUS P4P800 DELUXE SPRINGDALE RT

POWER SUPPLY ANTEC TRUE430 ATX RTL

CPU P4/2.4CGHz 800M 478P/512K HT RT

DDRAM 512MBTWINX512-3200C2 COR RT

HD 120GB|WD 72R WD1200JB 8MB-CACHE%

HD 36GB|WD 10,000 WD360GD 8MB

CDRW LITEON|52X32X52X LTR-52327S BK

SOUND BLASTER|AUDIGY 2 PCI SB0244 %

CPUFAN COOLERMASTER ISB-V73 AR4 RT

Raedon 9800 Pro 128 MB

 

You absolutly sure you put the harddrives back on the same cables they came off of? If you would have cable select on and you reversed a cable it might not find the OS properly. Also are you sure you didn't accidently bend or break any pins?

 

I have 3 HDs and I am pretty sure I hooked them back up right, only thing that i could have possibly switched is maybe the power cables to each one. One is hooked up with some red flat cord and the other 2 are hooked up to raid. I could have switched the ones on raid, but that wouldnt explain the blank screen. What pins are you referring to? Power pins or ones on my mobos? Or other ones?

 

My next plan is to reset the BIOS and start adding piece by piece. Board doesnt give off any noises. I did take off the processor, but its an intel. I put both it and the heat sink back the way they were, never had a problem removing them before. I really hope i didnt fry my board. Guess my only option is go piece by piece. What order should i had stuff? Should I get some kind of screen with just my mobo, graphics card, and ram? I know my raedon still works. And if it was my processor, shouldnt i still get a boot screen followed by a message saying no CPU found?