New
#11
Memtest passing just means the RAM modules themselves are good.
It does not mean theres not a memory problem, when everything is running together under load.
Double Check these:
Timings and make sure timings are set at the slowest of the 4 modules.
I/E 2 are 4-4-4-12 and 2 are 5-5-5-15 they will all need to be running at 5-5-5-15 DDR2800
Also Voltages.