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Prime Z370-A memory instability problems

Meeho
Level 7
Hi,

I have some issues with my new build with G.Skill TridentZ F4-3200C15D-32GTZKW 2x16 GB memory.

Intel i7-8700K
ASUS Prime Z370-A (BIOS 0605)
Win 7 Pro x64

*It fails Prime95 within 5-40 minutes with rounding errors at the rated 3200 MHz CL15-15-15-35-2T 1.35 V settings. I've tried VCCSA/VCCIO voltages in the 1.0-1.3 V range without success. CPU is running stock, Asus MCE disabled. What is interesting is that each stick tested individually works, but they fail when paired. If I bump the tRCD and tRP I regain stability.

MBO sets these timings:
CL - 15
tRCD - 15
tRP - 15
tRAS - 35
CMD - 2

RAS to RAS Delay L - 7
RAS to RAS Delay S - 6
REF Cycle Time - 560
Refresh Interval - 12480
READ to PRE Time - 12
FOUR ACT WIN Time - 34
CKE Minimum Pulse Width - 8
Write Latency - 13

tRDRD_sg - 7
tRDRD_dg - 4
tRDWR_sg - 16
tRDWR_dg - 16
tWRWR_sg - 7
tWRWR_dg - 4
tWRRD_sg - 32
tWRRD_dg - 25
tRDRD_dr - 7
tRDRD_dd - 7
tRDWR_dr - 16
tRDWR_dd - 16
tWRWR_dr - 9
tWRWR_dd - 9
tWRRD_dr - 9
tWRRD_dd - 9
TWRPRE - 42
TRDPRE - 12
tREFIX9 - 108
OREF_RI - 64

If I downclock the memory to 2133 MHz, I regain stability. I've also tried 3400-15-16-16-35-2T 1.35V and it's much more stable but still fails after about two hours. I've tried the other memory slots, bumping the DRAM voltage...same results.

Bad memory? Motherboard? CPU IMC?
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4 REPLIES 4

Exalanoto
Level 7
Try Vccsa and vccio to 1.20 and Dram voltage to 1.40

I have, still unstable. I've tested up to 1.45 V RAM and only at those volts have I managed to get them stable. At least for a couple of hours that I've tested at those settings, but I saw no point in letting it go longer as I wasn't comfortable running them that high just to get them stable at rated speed.

These run stable:

3200 MHz CL15-16-16-35-2T

... . . . . . . BIOS / HWiNFO64
DRAM : 1.3530 / 1.360 V
VCCSA: 1.1500 / 1.220 V
VCCIO : 1.1375 / 1.192 V

Heini
Level 11
The M.B. is rated up to 2666, anything above that is considered an O.C.
ps... 2x16 can be more difficult to deal with than 2x8 or 4x8 as long as they're bought as a "kit".

3200 @ 15-16-16-35 1.35 V is stable, though. Just finished a 10 hour Prime95 blend run at 95% memory usage.