Questions about a i7 920 Bloomfield OC.

[q011519]

So I've bee trying to OC my CPU for the past few days without any luck. I can't get higher then the "Dummy OC" that the Mobo does and what ever benefits I get from "Turbo" mode.

I can't think of what is holding me back. Any time I try and go higher my system just craps out.

These are the settings off the top of my head (currently at work)
Vcore is at about 1.3v
BCLK is at about 160 stable, anything higher and it craps out.
This is the RAM I have - OCZ Gold 12GB (6 x 2GB) DDR3 1333
but I can;t get my ram to go at those speed and be stable.
Mobo - EVGA E758-A1 3-Way SLI (x16/x16/x8) LGA 1366 Intel X58

Every time I try and OC it higher then 3.2ghz it becomes hell trying to get it up and running again. When I try and bring the Mem to run at about 1333 speeds it makes the computer no longer be able to post and keeps rebooting. Have to clear the CMOS to be able to get it up and running again.

If I leave the Mem alone and try and OC the CPU windows will no longer load. I get a BSOD with a "Machine_check_exception" error. (CPU error from what I was able to determine.)

What do you guys/gals thing? I know I'm not giving everyone all the information needed (I'll update the post when I get home) but I have a feeling that my mem is holding me back.

Thoughts? Tips? Help?

Thanks everyone

 

[iCyborg]

Is your RAM running at default 1.5V? It might need 1.65V for max rated speed, so you may want to try bumping that up if you haven't already.

 

[keto]

I don't have the same mobo, mine's a GA-EX58, but I have a C0 920 and was messing around with it last night.

One thing that I found that I had missed multiple times was the multiplier for the Northbridge, QPI multiplier. I don't know if you have that, but on mine default on auto was 20X but I backed it down to 16x/17x to run closer to spec. It immediately gave me more headroom for overclocking the BCLK.

The other thing, and I don't know if this is unique to Gigabyte, but even though my RAM can run at auto/SPD timings, I have to go in and set the timings all manually even though the values don't change. Again, my RAM is not the same as yours but similar to you, it won't run at its rating...in my case, I have to back down to 8x multi and run around 1333 when in theory at least, I should be able to run 10x for 1600ish.

Also, as above, I run my RAM at 1.640v. They say not to exceed 1.65 as there is some interaction with the cpu, don't ask me for details just parroting what I read.

Good luck.

 

[Makaveli]

This was a pretty good guide I followed a while back.

http://www.xbitlabs.com/articles/cpu/display/core-i7-920-overclocking.html

 

[Avalon]

Could just be a hardware limitation. I overclocked my buddy's i7 920 the other night, and all I did was go in, change BCLK to 166, save, and fired up Windows. Didn't even touch voltage. He ran Prime95 large FFTs for about 12 hours and all was fine.

I know his memory ratio is 1:3, so it's running at about 1000mhz...I'd try dropping your memory speeds and your uncore speeds significantly, to isolate just overclocking your CPU. From there you should be able to figure out what's holding you back.

 

[q011519]

Thanks for the reply guys, I'll try and give it a shot this weekend when I have some free time. I really thing it is my RAM holding me back but it is just a pain to try and get everything back up and running after I do a failed OC.

 

[Shmee]

most likely uncore related, as seems to be the way with these issues. raising BCLK messes with 3 frequencies, aside from the BCLK itself. memory freq, CPU clock, uncore clock. And then uncore:memory ratio and voltages have to be right too

keep in mind with bloomsfield, best bet is uncoreX=2memoryY+1 where X and Y are the multipliers. uncore CAN be brought higher though. but the higher memory freq/uncore freq/BLCK/amount of ram the higher the QPI VTT(uncore voltage) needed. This might be your issue.

 

[Interitus]

Something to try...

My EVGA 758 is super picky about my RAM timings. In reality, it should be better to manually set the timings, but this just isn't the case with my board. It hates manually entered timings for some reason. If I just set it to XMP and go at it, I chug all the way up to 4.2-4.3ghz. If I manually enter the EXACT same timings, it crashes around 3.6'ish. I've picked through the timings a billion times and I know they're right for the RAM. Even loosening them up doesn't help.

Another thing to check is dumping your RAM to 2T if it's not already there. For some reason, I've had a few kits that insisted on trying to run 1T at SPD for DDR3-1600 even when the specs claimed it only ran that way at 2T.

 

[QuantumPion]

My C0 920 goes up to 180 BCLK at default voltages but any higher than about 185 and I get BSOD's even when I crank up to 1.4 V on CPU and 1.35 V Uncore. They are just finicky that way I guess.