This is driving me crazy. I've been out of IT for a few years now and I guess I'm a little rusty. The motherboard on my media center computer fried so I decided to upgrade everything while I was at it. I got an Intel DH55HC mobo/i5 processor with an Antec 650w 'true power new' power supply, 4GB RAM and put it all back in my old case. After everything was installed I powered it up, the fans kicked on for about a 3 seconds and turned off. After about 5 seconds the fans kicked on. This cycle keeps going until I power it off. I get no error beeps and no video. My first thought was a bad mobo so I exchanged it and installed everything again. Same thing happened. Second thought was the power supply so I exchanged that - same thing happened. I tried a power supply out of another computer on the new mobo and the same thing happened. I tried the power supply in another computer and it booted fine. Could it be a mobo/psu compatibility problem or possibly the processor?