OK, power supply it was, I actually had to wait about 8 minutes even to pull it out, it was VERY hot. It has a massive failure by the look and smell of it, but the server has turned back on and the RAID is showing to be in good shape. I expect we will have a fsck however as it was a very rough and abrupt shutdown. This will be 15-20 minutes time and then should return to up if all goes well.