Gigabyte board i5 2.8 quad cpu 750 watt psu. When computer is turned on it turns straight back off all the fans spin up and it emits a short bleep and will repeat this till system is turned powered off. System does the same with everything unplugged except cpu and power installed. Board psu or cpu failure?
One short beep is the BIOS telling you that there is a memory failure. Maybe try running memtest86 for a couple hours? Just a suggestion. ETA: I should have asked what BIOS? Just realized the beep codes are going to be different. I found this: http://www.5starsupport.com/info/beep_codes.htm
The bleep was misleading and was coming from the front panel lol was the last thing I unplugged in desperation. The board dont bleep or post just starts up and instantly switches back off and repeats the cycle over and over again till powered off. Think me really needs another i5 board to test cpu and the the board. Even when stripped down to board and cpu same thing.