Ripper Price on the Memory, maybe should have moved to the states instead of Arctic UK...More information !!!
1) are you running W7-64 Ultimate or other ?
1a) are the dimms reporting to bios during boot correctly and at what speed...UD3Rs have an annoying habit of applying 1066 when ever it has trouble posting
1b) if not posting correctly,...manually configure in bios
2) are you targeting the white slots only ?
3) have you tried "Memtest" on all three DIMMs
4) if it fails test, run memtest on individual dimms in there home slot
Might not be the final fix but if you do these things will take a lot of things out of the equation....the first few thing I would try anyway!
Aussie Allan