Hi LSD thanks for replying.

I haven't been using 2000Mhz much, just for running Memtest as I figured it would bring about any problems quicker. I've used the XMP profile which sets the Vram at 1.65v and QPI at 1.7v. I have left the IOH on auto.

Otherwise I've mainly been using 1600/1866Mhz. For this I had voltages set at 1.65Vram and 1.6 QPI, as this is set by XMP. Other voltages on auto. I've also just left everything on default, I think the memory is 1066 on defaults, and the problem has still occured (albeit after about 16 hours 100% strest test).

The memory was suspiciously half price from say the Corsair Dominator equivalent, I just figured that was pricing strategy. I think I may have to investigate new memory...

Anyway, here's my settings I'm using currently:

CPU = Intel i7 920 D0 (SLBEJ) 2.66Ghz
Motherboard = Gigabyte EX58-Extreme revision 1.0
BIOS = Currently F8b as it seems the most stable, but tested F5-F8b
RAM: Kingston HyperX 6GB (3x2GB) DDR3 2000MHz CL8 (KHX16000D3ULT1K3/6GX) Link = Kingston HyperX 6GB (3x2GB) Intel XMP DDR3 2000MHz CL8 Triple Channel (KHX16000D3ULT1K3/6GX)


Advanced CPU Features:
CPU Clock Ratio ................................ [20x]
Intel(R) Turbo Boost Tech .................. [Enabled]
CPU Cores Enabled ............................ [All]
CPU Multi Threading .......................... [Enabled]
CPU Enhanced Halt (C1E) ................... [Enabled]
C3/C6/C7 State Support ....................[Enabled]
CPU Thermal Monitor ......................... [Enabled]
CPU EIST Function ............................ [Enabled]
Virtualization Technology ................... [Disabled]
Bi-Directional PROCHOT ..................... [Enabled]


Uncore & QPI Features:
QPI Link Speed .............................. x36
Uncore Frequency .......................... 3733
Isonchronous Frequency ..................[Enabled]


Standard Clock Control:
Base Clock (BCLK) Control ................ [Disabled]
BCLK Frequency (MHz) .....................133
PCI Express Frequency (MHz) ........... [Auto]

C.I.A.2 [Disabled]

Advanced Clock Control:
CPU Clock Drive ..............................[800mV]
PCI Express Clock Drive ................... [900mV]
CPU Clock Skew ............................. [0ps]
IOH Clock Skew ............................. [0ps]


Advanced DRAM Features:
Performance Enhance ...................... [Standard]
Extreme Memory Profile (X.M.P) ......... [Enabled]
System Memory Multiplier (SPD) ........ [AUTO]
DRAM Timing Selectable (SPD) .......... [Manual]

Channel A + B + C

Channel A Timing Settings:

##Channel A Standard Timing Control##
CAS Latency Time ......................7
tRCD .......................................8
tRP .........................................7
tRAS .......................................20

##Channel A Advanced Timing Control## - All these are set to auto but show as follows
tRC ........................................42
tRRD ....................................... 7
tWTR ...................................... 7
tWR ........................................ 14
tWTP ....................................... I dont seem to have this option
tWL ........................................ Or this one
tRFC .......................................70
tRTP .......................................7
tFAW ......................................28
Command Rate (CMD) ................1

##Channel A Misc Timing Control##
Round Trip Latency ...................51



Advanced Voltage Control:

CPU

Load Line Calibration ................. [Disabled]
CPU Vcore ...............................1.23750 (auto)
QPI/VTT Voltage 1.150v ............(auto but set by XMP to 1.6)
CPU PLL 1.800v .......................[Auto]

MCH/ICH
PCIE 1.500v ...........................[Auto]
QPI PLL 1.100v .......................[Auto]
IOH Core 1.100v .....................[Auto]
ICH I/O 1.500v .......................[Auto]
ICH Core 1.1v ........................[Auto]

DRAM
DRAM Voltage 1.500v ..............(auto set by XMP to 1.65)
DRAM Termination 0.750v [AUTO]
Ch-A Data VRef. 0.750v [AUTO]
Ch-B Data VRef. 0.750v [AUTO]
Ch-C Data VRef. 0.750v [AUTO]
Ch-A Address VRef. 0.750v [AUTO]
Ch-B Address VRef. 0.750v [AUTO]
Ch-C Address VRef. 0.750v [AUTO]

Thank you so much for your help, hopefully you can spot somewhere where I might have gone wrong!