Memory LowGap

[MasterPlan1]

Hi, I seem to be having some issues building a new system of mine - I'm pretty sure it's owing to lowgap settings, or it might not be - either way, I'm completely clueless as to what is going on, basically - I've got 24Gb of RAM, 12Gb works, both sets of 3x4Gb - but when I have all 6 banks filled - no boot, the board is a DFI LanParty Jr X58-T3H6, when I boot it with all 6 slots, it comes up with 3F on the diag LEDs... I've tried setting the lowgap to 3G, 2G, and 1.5G - the graphics card I have is a measly 8600GS 512Mb (waiting on the 6770 I want to come in) so any of the above lowgap settings should work for it. I've flashed the bios to the latest, so shouldn't be any bios issues...

Any ideas? As I'm not used to the X58 arch, so not sure what else I should be looking at.

Thanks