ASRock X58 Extreme no OC but 6 DIMM's very unstable in Prime95

[Aresbowman]

Hi,

When I install all 6 DIMM's, running Prime95 results in nearly all core threads failing immediately to within 3min due to a P95 error description of a "rounding error". If I run the three primary DIMM's the system is stable using either of the sets of RAM, in other words the problem doesn't seem to be the RAM since both sets of 3 sticks run stable when installed in the primary DIMMs. This is occuring at default settings for the BIOS. The only potentially odd thing I have noticed is that the AUTO settings on the BIOS are setting the RAM at 8-8-8-20 even though the RAM spec is 9-9-9-24. I tried manually setting the RAM to 9-9-9-24 and still got the P95 failures described above. I posted this on the ASRock website and someone suggested that I post here as well in case anyone has a different insight. Any thoughts?

XSRock X58 Extreme (current BIOS)
Intel Core i7 920
G.Skill DDR-3 1333 9-9-9-24 1.5V 2GBx3 (F3-10666CL9T-6GBNQ)

Thanks

[Tradesman]

Mixing two or more sets of DRAM, even the same model can be problematic, the sticks may not want to play together, that being said, you can normally get them to play wit some voltage and/or timing adjustments. First, you'll want to make sure you have the latest BIOS, then install all and go to BIOS, set basic timings to 9-9-9-24, CR (Command Rate) to 2T, DRAM Voltage to 1.65, and not sure what your QPI/VTT voltage is at so let's start by raising it + .06...and see how that does

[GSKILL TECH]

Make sure each kit is installed in the same color slots. It is possible the two kits can not fully match.

Try DRAM Voltage 1.550V, everything else AUTO should be OK

Thank you
GSKILL TECH