[damien c]

Well I had a similar issue and still do with my current Gigabyte EX 58 Extreme Motherboard.

It will loose all the drives except for the C: Drive, and I tested the drives in another machine and on another 2 boards and they worked fine.

I know the Sata Chipset on the board is faulty but to be honest at the moment I cannot send it off because it only, does it if the cpu is overclocked but when it's at stock speed it run's fine at the moment but the second it does it at stock speed the board is off to Gigabyte.

Try swapping the port's etc because most Gigabyte board's have 2 different sata controllers on them, which 1 of them may have gone faulty unless it's only the Intel Gigabyte boards have 2 and the AMD don't.