Overclocking i7 920 to 3.8GHz - high voltages but still unstable!

richbosworth · Jul 30, 2013

Hello,

I am new to overclocking and am trying to push my old i7 920 to 3.8GHz. However, I just can't seem to get it stable! I have this CPU water cooled and the case has 3 exhaust fans up top, a 200mm fan on the side drawing air in through the case and a fan at the front bringing cool air in.

I'm trying to follow guides and have researched other people's results, but I just can't get the settings right. I've spent a few hours trying to figure this out on my own, but I hope you can help guide me in the right direction!

I believe the voltages I'm having to set to achieve even temporary stability (<20 minutes prime95) are way too high. Is this correct?

I'll post up my BIOS settings as that's probably easier to read for you guys familiar with the OC process:

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This community's been absolutely fantastic so far, so I hope that I've come to the right place for this!

Thanks in advance,
Richard

Hard Line · Jul 30, 2013

increase IOH to 1.3 and see what that does for you. also how many dimms do you have installed?

Also you have access to 21 multiplier. I would use that so you can use a lower bclock. what cooler are you using?

You can re enable speedstep as well. it does not reduce stability anymore. and sometimes causes instability being disabled.

richbosworth · Jul 30, 2013

Thanks for the quick answer!

I've increased the IOH to 1.3 but it remains unstable keeping the other settings constant. It also remains unstable under a 21 multiplier with a BCLK of 181 to get to 3801MHz.

I have the Corsair H55. This keeps the OC idle temperatures at about 40-43°C, with just pre-crash temperatures at about 70-80°C.

Also, are there any recommendations about the RAM multiplier? Is it best to stick around 1600 or should I set it lower/higher?

I also read here (http://forums.tweaktown.com/gigabyte/47945-cpu-pll-effect-overclocking.html) that it may be an idea to set the PLL voltage lower/at stock?

Hard Line · Jul 30, 2013

keep teh ram as close to 1600 as possible. yes keep pll at 1.8. also make sure to manually set the primary ram timings. I have seen many board mess them up. try increasing QPI 1 notch higher. what voltage is your ram rated at? make sure voltage is corect. and keep in mind you wnat the dram voltage within 0.3v of the qpi or you will become unstable. You want to increase LLC ( load line calibration this setting is called differnt things depending on manufacturer. mine is set at level 2 ) set ICH voltage to 1.24v try IOH at 1.32v, enable C1E. Let me know how that goes.. I will read it tomorrow am as I am on my way to bed for the night.

richbosworth · Jul 31, 2013

Hi I did all of those things, and it seems as if now my OC is fine for playing games, but when I run Prime95, it is unstable. I'm worried about pushing the voltages too high! Is the fact I've got all of my DIMM slots used a problem?

Hard Line · Jul 31, 2013

ok thank you for finally answering that question lol.. all dimms occupied means you need higher QPI voltage. when P95 errors.. does it just drop cores, or does it cause a bsod? also what speed ram is it? I have mushkin redlines at 1600 and I need 1.413v on my qpi with a 205 bclock ( running 4.3ghz )

richbosworth · Jul 31, 2013

Sorry about that!

P95 causes BSOD consistently. As I increase vcore, the time before BSOD lengthens. I've upped the vcore to 1.39 and this results in BSOD after about 14 minutes.

My RAM is @1600 http://www.corsair.com/cmx4gx3m2a1600c9.html

EDIT: Although now I'm looking at SpeedFan and it appears at the 1.39 voltage, the usage with P95 is gradually decreasing from 100% to 0%. What does this mean? Is this what dropping cores is?

Hard Line · Jul 31, 2013

That ram needs 1.65v to run at the rated speeds. ( have you manually set the timings? ) You linked me to a 4GB kit did you purchase 3 4GB kits to fill all slots? also you may need to increase the vdimm due to the higher qpi needed. my particular chip prefers to stay within 0.3v of each other. some are more lenient at 0.5v ( also mainboards tend to undervolt the ram ( at least mine sure does ) what is the bsod you are getting? 101 or 124?

richbosworth · Jul 31, 2013

I haven't set the timings manually, so I believe they're all still on Auto (to be honest, I'm a little bit intimidated by the motherboard's timings interface). The motherboard has all 6 slots filled, so it would be 6 x 2GB.

Would VDIMM by the same as DRAM Bus Voltage? (I've set this to 1.64v, but if I try to raise it to 1.66v it gives an error stating that over 1.65v can damage the CPU).

I'm not sure how to see the BSOD error, as it's windows 8 so just a smiley face. Is there a way to access the BSOD error message? Edit: it just comes up with WHEA_UNCORRECTABLE_ERROR

Hard Line · Jul 31, 2013

ok .. manually setting the major timings is easy everythign on aut except the first 5 timings and just input what the ram says. that is pretty fool proof for you. as for voltage. you may need up to 1.7. ( though it will really be a little lower anyhow. I have been running 1.7v with no issues for years. though 1.66 opr 1.68 would be better. it's actually worse to have a higher ratio between vdimm ( dram bus voltage ) and qpi. the warning is just more for information. Someone who is deliberately doing this generally knows the limits or is being guided. download blue screen view and you can see the bccode

richbosworth · Jul 31, 2013

Okay, I'll take a look at the RAM timings now.

I've actually managed to get a somewhat stable OC (Prime95's been running for 45 minutes - I know that doesn't say too much, as it's too short, but it's 30 minutes longer than my previous max's). However, the voltages are fairly high:

Vcore: 1.39375v
PLL: 1.88v
QPI: 1.39375v
DRAM is at 1.66v
The BCLK is at 181 and the CPU Multiplier is 21.

Should I stick with these settings (assuming that Prime95 runs okay for a few more hours), or would implementing some of your latest suggestions help increase stability/decrease the needed CPU voltages etc (they seem very high at the moment, for 3.8GHz).

I'll download that BSOD program and if there is an error I'll post up the bccode.

richbosworth · Jul 31, 2013

Okay looks as if it's still unstable. hmmm I must be doing something majorly wrong here!

Okay, the error code is 124.

Hard Line · Jul 31, 2013

if you can get a prelim p95 test for 2-3 hours . that will be a decent base ( not 100% stable but something to work with ) we can go for 100% after. what cooler do you have? we need to keep temps below 80 and lower if possible

richbosworth · Jul 31, 2013

I've got the Corsair H55 and it keeps temps under 80°C currently (about late 70s). I edited my last post with the error code: 124.

I changed the overclock setting from Manual to XMP and that seems have to increased overclock stability. Prime95 has run for 1 hour so far.

Hard Line · Jul 31, 2013

ok looking good. if you like, you can stop it and we can try lowering voltage ( or you can increase clocks little by little and try for 4.0 lol )

richbosworth · Jul 31, 2013

Lowering the voltage even one step resulted in instability. I guess I'll have to stick at this voltage for 3.8GHz. It gives temperatures of around 60°C when gaming, which I guess is fairly reasonable, and as mentioned, late 70s when Prime95 is running.

Anyway, thank you so much for helping me get a fairly stable OC.

I guess it's mostly just trial and error. However, as a 'noob', your guidance massively helped me understand what was going on! As this was a sort of ongoing conversation, it was rather difficult to select a single answer as a solution, so I've picked one of the answers with the most details in.

Hard Line · Jul 31, 2013

Thank you very much it is appreciated. if you have any issues or need more guidance, you can come back here or you can pm me. I will be more than happy to help you continue your endeavors

Overclocking i7 920 to 3.8GHz - high voltages but still unstable!

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