2000Mhz unobtainable - but RAM is rated for it

I'm OCing my first PC (woohoo! Quite fun)

Problem:
I'm unable to attain 2000mhz on my ram without BSOD. I believe the problem is with the Uncore multiplier, I've read that you must maintain at least a 2:1 ratio between Uncore and ram speed. Any time I try to maintain that, I crash while getting into Windows. It does POST though.

Specs:
Corsair Dominator GT 6GB kit CMT6GX3M3A2000C8
Gigabyte GA-X58A-UD3R firmware FA (latest I believe)
i7 930 CPU, D0 revision
GTX 480 (SLI)

BIOS Settings:

CPU clock ratio x16
QPI ratio x36 (7.2Ghz)
Uncore x16 (3200mhz)
Bclock 200mhz
System memory multiplier is 8. Memory is running at 1600mhz currently
Timing is set to 8-9-8-24 1T

CPU Vcore 1.3v
QPI/Vtt 1.375v
IOH Core 1.34v
DRAM 1.66v


The guide I'm working with is the "3 step guide to OC your core i3/5/7"

I'm on the stage where you test the memory. I've gotten the Bclock up to 210mhz without any issue or additional voltage, figured that was enough for where I wanted to be speed wise and moved onto the memory testing. My Mobo doesn't have a memory multi setting, but I think that is the Uncore setting, and I just have to do the math to maintain the 2:8 ratio.

Once the memory issue is addressed, I guess I'll go for max OC on the H50 cooler and see where I can get while being below 80C.

Thanks for the help!

Well, if your RAM is running 2GHz, that means your uncore will be at 4GHz.

Try booting with the uncore at a lower multi. If it works, go with it. Not sure that uncore voltage can be adjusted. If it can, someone please chime in

In order to hit DDR3-2000 you'll probably need to bump QPI/VTT voltage to ~ 1.58V, along w/ these other settings at a 200 BCLK...


... and change the Command Rate from 1T to 2T at 1000MHz.

Thanks CompuTamer - I can change the uncore multiplier, but I don't think I can lower it much. I have not tested, but my guess is that I can't get a bclock of 250, which would be necessary to get the uncore at 4000mhz on a multi of 16.

Hey duc driver

I'm currently running the suggested settings, so far one pass of memtest complete without issue! Thanks.

I would love to understand more about why so many voltage changes were necessary, and what overall effect they have on the system. If you have more time I'd like to learn about that. In the meantime I'll get my search shoes on and try to figure it out myself.

I

Update-

Running at 3.8Ghz on CPU now (200 bclk, 19x multi)

CPU temps are getting high with the changes Duc suggested, like 83c vs 78c with the slower ram settings.

Benchmark wise, I see very little change in futuremark score (1K+) for the new ram.

My guess is I'll probably end up dropping ram speed, for timing gains, lowering various ram related voltages for a higher CPU multiplier which will overall improve machine performance.

Lower the QPI/VTT voltage (uncore) from 1.58V 1 step at a time, running Memtest86+ after each subsequent drop until it fails. After it fails bump it back up to the next step, or to the lowest level required to run stably at 1000MHz.

thx247 said:

My guess is I'll probably end up dropping ram speed, for timing gains, lowering various ram related voltages for a higher CPU multiplier which will overall improve machine performance.

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2k ram is only good for benching. not much real world gains. Should have went low timing DDR3 1600 (cas7) and saved yourself some money.

Yeh had I known, I could probably have saved another $100 somewhere in there. Its alright though, I can spend some time learning about OCing ram timing.

Looking online again, there is a CAS 7 2000mhz kit for only 20 bucks more, same vendor and manufacture. 20-20 hindsight!

Later today I'll try lowering my bclk, going with a higher CPU multiplier hoping for lower temps. The ram will decrease in speed as well which lets me lower voltage on QPI...overall lower voltage in CPU = lower temps.

This stuff is fun!

EarthDog said:

2k ram is only good for benching. not much real world gains. Should have went low timing DDR3 1600 (cas7) and saved yourself some money.

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