Computer Turns on, but no POST, video, beeps

[raserdemon]

I recently bought a new CPU cooler for my system and installed it. After putting everything back together and powering it back up, everything came on but there was no video coming out. I checked all the connections and such, couldn't find anything, so I got a motherboard speaker and hooked it in to check for an error code. When it powers on there is no sound at all from the speaker, which I tested to make sure it was working and it is. There isn't even the one beep that its supposed to make when everything is ok. Immediately suspecting a video card problem, i swapped in another one which I know is working. Same thing. There's no onboard video so I can't try that. I've swapped memory, tried starting with bare bones only (board, memory, cpu, psu, graphics, keyboard), and keep getting the same result. Any ideas as to what's going on?

System Specs:
Gigabyte MA790FX-DS5
AMD Phenom X4 9800
ATI Radeon HD 5750 1GB
2x Corsair 2GB DDR2
2x Corsair 1GB DDR2
2x Seagate 320GB in Raid 0 (Boot Drive)
1x Seagate 1TB
Coolermaster GX 750W
LG DVD-RW

 

[knightdog56]

Did you plug the cpu fan in correctly? Is the new cpu fan and heatsink a 4 pin or 3 pin connector?

 

[Guest]

I'd put my money on you incorrectly installing the cpu cooler or fan. Have you got enough thermal paste? remember don't put too much.

 

[henydiah]

check back ... make sure the pin CPU net of thermal paste, try again with the PSU, Mobo + speakers, use the stock cooler first and then turn if hearing beep then it is correct, if you have not heard it could be the mobo / cpu errors,

 

[scout_03]

check everything inside could be just a power cable loose or memory stick if you have remove them that are not back in correctly

 

[raserdemon]

I've reseated the heatsink to make sure it was installed correctly and the fan does spin when I power the system on. Still no luck. I'll try putting the stock back in and see if that does anything for me. I've gone over everything in the case, took the entire thing apart and put it back together to make sure I got everything. Memory is all seated properly and I suppose I could run a test on it to make sure it's ok. I'm suspecting either a CPU, or more likely, motherboard or psu problem though because of the lack of beep codes when I turn it on. Is there any way I could test my CPU/board? I'll find a psu to swap that out and see.

Thanks for the advice so far.

 

[dodger46]

No easy way to check CPU unless you buy a cheap Sempron from Ebay (Sempron 140 for around $10 or less) to see if that works. Did you inspect your CPU minutely for bent pins? Preferably with a magnifying glass, they're hard to spot... if you find one straighten carefully with a fine tip. (I used a scalpel!)

 

[raserdemon]

I have tried another power supply, put the stock cooler back on, tried removing memory, removing video card, still no luck. I could find nothing visibly wrong with my CPU so the issue must lie with the motherboard. I'm checking the warranty status/shopping for one now, hopefully that's the issue and not the CPU. Thanks for all the help everyone.