I bet you don't see this request often! Under-clocking

[AzJazz]

Hi -

I just purchased 16 GB of G.Skill 2133 DDR3 RAM. (F3-2133C11Q-16GAO)

I am trying to install it in my Asus P6T Deluxe V2 motherboard. Even though the NewEgg Memory Selector said the RAM would work, it doesn't. My PC never boots out of the BIOS. My BIOS claims to go up to 2000 DDR3 (and, I see BIOS settings up to 2400),but it doesn't seem to work when I select either of the XMP settings (2133 and 2000)

I am replacing 6 GB of Corsair 1600 DDR3 memory.

Can I get the G.Skill to work at either 2000 or 2133?

If not, is there a way to underclock to get the G.Skill RAM to run at 1600?

Note: The G.Skill RAM runs OK at 1066.

Thanks!

AzJazz

 

[jazon1]

there should be a XMP setting for 1600 in there,if not just try to adjust timings to get yourself at 1600.

 

[redduc900]

You'll need to increase the QPI/DRAM Core voltage (VTT) to run 16GB at DDR3-2000 and above. Take it off Auto (1.15V) and bump it up to 1.35V to start with, setting it to no higher than 1.55V. And manually adjust the timings to 11-11-11-30-2N at 1.60V DRAM voltage.

 

[Woomack]

2000+ depends from cpu. On Bloomfields it's usually waste of time. If you have Gulftown then it should work @2000-2133.

 

[AzJazz]

Thanks, guys! My CPU is a Core i7 920 from about 5 years ago. The BIOS built-in memory option skips over 2000 for some reason, and goes from 1866 to 2133. Using the memory's XMP Profile settings for 2000 modified the BCLK value, which really borked things up - I saw BIOS corruption messages.

I tried to set the memory for 1866, and had mixed results. My system would boot, but it only recognized 12GB of the 16GB available. The first couple of minutes of MemTest86+ 4.20 passed, but I would expect it to fail at some point due to the incorrect memory detection. Modifying the QPI voltage did not seem to help.

Right now, I have MemTest86+ running with the memory configured for 1600 @ 8-8-8-24-2N, with the QPI voltage at 1.2 VDC. All 16GB was recognized. (Note: I just got home, and MemTest86+ ran for 8 hours with no failures)

Should I be raising my QPI voltage (or, any other values) for more stability? Does anybody know what the max voltages are?

 

[Woomack]

For higher memory clocks you have to set higher QPI/VTT voltage. Also if you are setting higher bclk then QPI/VTT will be higher.
On my i7 950 I needed about 1.4V for 200bclk and 16GB (4x4GB) @1680 7-7-7.
Check if your memory is working in triple channel and if it's not then use slots 1, 3, 5, 6 counting from cpu side ( it's probably marked other way on the board ). It was working as triple channel on my board this way using 4 sticks.

I said that 2000+ has no point mainly because there is not big difference in performance and it's much harder to stabilize IMC. To make it stable you will need 1.45-1.55V+ QPI/VTT and probably also higher IOH voltage like 1.18-1.25V.