Might not have been the slots, but I think somethings iffy with the memory.
It was working fine last night, and even this morning.
I turned it on after work, and decided to go into the BIOS to check things. All well and good, so i exited. It reset, and suddenly (even though the RAM is set to automiatcally configure) it set itself to 816mhz, not 800, and wouldn't boot into Windows. Came up with a corrupted Windows file.
Anyhow, I took the sticks out, and put them back in again, and started it up. Clocks were fine again, and Windows booted.
Shame, it is now having to rebuild the RAID in Windows though
I guess I just shouldn't enter the BIOS...
If I could find out the right timings though to set it myself, I guess I wouldn't have the problem with the RAM being overclocked without me doing anything.
I know its 4,4,4,12, but thats about it