Cheers for the response
I've got a GT730 on the way so will try that too, will also try the 5450 in the top PCIE Slot.
The most I've booted is 120MHz on G7400 and I use GTL to increase in OS. Once I hit 129MHz it instantly freezes and then will sometimes bsod. Generally see IRQ not less or equal than, and memory management errors so I think you're right memory could be the issue.
I've had memory down quite low already, I found the lower the strap the more bclk I could get, like if I was at 4800Mhz and dropped down to 4000MHz I'd gain 1-2Mhz bclk
I'd like to try a G.Skill kit too but these memory kits are expensive
I'll try the 5450 in the top slot first and see what happens
EDIT
Tried your profile with a couple changes, I turned off LAN and Audio, also I set memory clock to 6200Mhz as opposed to 6800Mhz
Can't get past POST with the settings. I tried to increase VDD/VDDQ to 1.45v, but still wouldn't POST, the debug code ends at 54 then goes through the post cycle again and again and again. Is it possible this board just doesn't like the Corsair Vegeance sticks? Or is the board likely a problem, a bit like the early Asus boards where?