It's a P5W DH Deluxe.

The manual says it supports 8gig 2 per slot 4 slots I'm almost sure the last slot is not working. Have already swapped the ram around to check that's ok, put 1 stick at a time into slot 1 and they all showed up as I have 32bit windows 7 there is no point having any more than 4gig hence the orignal post.