Just built a new PC and apart from a few hickups (burnt out psu etc). It's working but the main problem is the front usb and audio won't work, they both constantly think things are been plugged in a disconnected, constantly. So windows is constantly popping up the device connected/disconnected box and sound. Unplug them all and the PC works fine. Antec 100 case Gigabyte PH67-UD3-B3 mobo. Rest of PC is GTX260, I5 2500, 4GB ram. Any ideas? Checked the mobo headers and is correctly connected, have also tried just one usb (case has 2 usb + one audio), does it regardless of the combo used. Oh yeah, could PSU only had one 4pin cpu power cable not the two on the mobo, but it works fine, that won't be it will it? Also the CPU is only a i5 2500 (NOT a K), and it's running at 3.4 not the default 3.3?
Have you checked your setting in the motherboard BIOS? I know on mine, you have to enable the front audio and USB ports.
Not sure, I mean I went through the bios and didn't notice any but I wasn't looking for that specifically. Just seems strange that it is obviously detected it just things things are been pulled in and out. Also strange how the CPU is running faster that it's spec. I'll have a look when/if I next go round, he's under strict instructions to not touch or fiddle with his PC as he has broken every single one he has ever owned.
Replace the cables, or just find an old front panel and use it to make sure it isn't a problem with them.