Got back Monday night...but I've been trying to finish the memory testing since. Got some info and some questions for you memory experts out there. May post this in the memory thread also.
Background: After a couple of bad kits and required RMA's, I've ended up with two separate 32GB Corsair Dominator GT kits with rated specs of 1,866 MHz at 9-10-9-27 timings. So....8 sticks total, at 8 GB per stick, for 64 GB total.
I've successfully tested each kit individually (4 sticks at a time) at the rated specs, and they run flawless. 12+ hours of memtest86 with no errors, and 12+ hours of Prime95 blend. No issues. And no heat issues either.
But....when I try and run all 8 sticks at the same time, at rated specs, I can't get the machine to post. And I've tried loosening the timings at various steps all the way up to 14-15-14-42, and still can't get stability. I can usually get the machine to post and windows to load if I increase voltage just a touch to 1.51 volts, but then Prime95 fails quickly. I've tried increasing voltage, at different timings, in small steps all the way up to 1.59 volts, with no success. When I research online...it sounds like my experience is not unusual. Apparently not many IMC's will run 8 sticks at more than 1,600 MHz.
So...next I turned the frequency down to 1,600 Mhz, and was able to successfully run memtest86 and Prime, with all 8 sticks, at the rated timings of 9-10-9-27. Rock solid. I played with tightening up the timings some, and got down to 8-8-8-24 while staying at 1.5 volts, and 1,600 MHz. That's the best I could do with all 8 sticks and 64GB installed.
Next I decided to see what kind of overclock I could get on just 4 sticks (or 32GB). I manually adjusted frequency to 2,133 MHz, and loosened up the timings significantly to 13-13-13-37. At first it wouldn't boot...but I gradually increased DRAM voltage in 0.1 increment steps....and once I got to 1.56 volts, I could boot the machine into Windows. memtest86 and Prime95 blend ran flawlessly. I started tightening up the timings one bit at a time, and got down to 11-11-11-31 and could still run memtest86 and Prime95 blend flawlessly. However, at 10-10-10-29 and 1.56 volts, it wouldn't boot. I dialed back a notch to 10-11-10-30.....and I could boot again....but it failed Prime95 quickly. I increased the DRAM voltage to 1.57......and now it runs memtest86 and Prime95 flawlessly again.
It takes time to zero in on the tightest timings for a given frequency and/or voltage. I'm going to keep tweaking...and probably can get a little bit better. But I wanted to ask you memory experts out there a question and hope for some constructive comments also.
Right now, I could choose between the following setups that have proved stable:
a) 64GB (8x8) running at 1,600Mhz and 8-8-8-24 timings, and 1.5 volts
b) 32GB (8x4) running at 1,866Mhz and 9-10-9-27 timings, and 1.5 volts
c) 32GB (8x4) running at 2,133Mhz and 10-11-10-30 timings and 1.57 volts
Questions for you:
1) Which of the 3 scenarios above would you choose and why?
2) Any suggestions for trying to reach 1,866Mhz with all 8 sticks installed?
3) Will any of the setups unduly hinder my future CPU overclock goals?
4) How bad is it to run 1.5 volt memory at 1.57 if you keep it up 24/7?
5) Max DRAM voltage I should consider safe for a 24/7 box?
Thanks in advance!