System Locks: EVGA P55 FTW + F3-12800CL9D-4GBRL(x2)

[MNParadox]

Here's my setup:
EVGA P55 FTW
Intel Xeon X3440 @2.53GHz
Xigmatek Dark Knight HSF
EVGA 9800GTX+SC GPU
Raidmax 700W PSU
GSkill F3-12800CL9D-4GBRL (2 sets, 8GB total)
Western Digital Caviar Black 640GB SATA HDD

Issues:
Windows 7 Pro 64bit installed without a problem. The system will lock up randomly after 5-10 minutes in Windows. No BSODs. Memtest86 v3.5a tests all RAM sticks individually OK after 5+ passes. Same results with any combination of 2 RAM sticks. However, if all 4 sticks are installed, Memtest86 hard-locks at 5% overall every time (I can't recall which test it is).

Is this a timing/BIOS setting issue or is the motherboard bad?

Please provide the correct timings that I should manually set.

Thanks!

[Tradesman]

Could you post your BIOS settings, prob need to raise DRAM voltage as well as system voltages to handle 4 sticks

[GSKILL TECH]

It is also possible that the two kits are incompatible.

Thank you
GSKILL TECH