Corei7 920 OC & Temperatures.

[RiGoRmOrTiS]

Hi all,

Before I begin; my PC spec:

Intel Corei7 920 (C0, not D so 20x Multi) 2.6Ghz.
Thermal Take TruBlack 120 Cooler with 120mm fan
6GB G-Skill DDR3-1600 (3x2GB)
Asus P6T Deluxe Motherboard
2 x NVidia GTX 460 (SLI)
850w PSU

Now down to the issue. I'm attempting to over clock my CPU to 4.0Ghz with acceptable temperatures; on air cooling. I'm told it's possible on air-cooling; however I would be willing to go down to 3.8Ghz if that helped my situation.

At 4.0Ghz or 3.8Ghz I'm idling at 50-57c and under 100% with Prime95 it quickly raises to 99/100 at which time I stop it since that obviously too high.

even at 3.2Ghz I'm idling at 47-50c and hitting a max of 80c on Prime95; which for such a low overclock seems unacceptable.

Now there is always the possibility I need to clean and re-sit my heat sink; I think I was too liberal with the thermal paste when I originally put it on and this will be investigated tonight.

However do any of you kind folk have a cooler recommendation for over clocking at 4.0Ghz while keeping in mind I would like to avoid water cooling; budget constraints etc..etc..

I also have a feeling my case may not be roomy enough for decent air-flow and cabled management. I've had to shove excess cable into empty drive bays which blocking the front case fans a bit. So with this is mind a reasonably priced PC case recommendation would also be helpful.

Thanks for any assistance any of you can provide

 

[HW91]

I don't think 4GHz was possible with C0's

any way try setting the vcore to 1.38v, QPI to 1.35v and try it then

 

[RiGoRmOrTiS]

I don't think 4GHz was possible with C0's

any way try setting the vcore to 1.38v, QPI to 1.35v and try it then

well i set BLK to 200 with 20x and its 4Ghz and memory is clocked at 1603 which seems right too. I have left all the Voltages at Auto though.

is vcore of 1.38v not quite high? (i.e. big temperature) I've heard its best to keep it in the 1.2x range?

 

[rjk]

my C0 did 4.2ghz at 1.38v

the voltage range is lower for a D0 cpu

a C0 920 has the same 20X [21 with turbo] multi as the D0 920

its less attainable, still possible but it does need more voltage

seems that your heatsink isnt handling the overclock well. those temps are too high. you want to be at around 80'c under load.

put the bclk to 160X20 then add 10 to the bclk and test each time.

start at around 1.4v and leave it there until you get the highest stable bclk

then work the voltage down in steps

 

[RiGoRmOrTiS]

my C0 did 4.2ghz at 1.38v

the voltage range is lower for a D0 cpu

a C0 920 has the same 20X [21 with turbo] multi as the D0 920

its less attainable, still possible but it does need more voltage

seems that your heatsink isnt handling the overclock well. those temps are too high. you want to be at around 80'c under load.

put the bclk to 160X20 then add 10 to the bclk and test each time.

start at around 1.4v and leave it there until you get the highest stable bclk

then work the voltage down in steps

I'll try these when I get home; do you think the heatsink I have is suitable (its bloody huge). I'm going to clean and re-sit it tonight but would be nice to know if its good enough.

also what load temperature should I consider "stable" before I start knocking the voltage down?

 

[Freakbro]

With Stable, i think he means the PC stable, ie : not crashing with Prime 95 etc

So start with 1.4v , get stable at the speed you want, then work the voltage down to find the lowest voltage the pc is stable with at your desired speed.

voltage = heat, so the lower you can get your voltages and stay stable, the lower the temps will be.

 

[RiGoRmOrTiS]

With Stable, i think he means the PC stable, ie : not crashing with Prime 95 etc

So start with 1.4v , get stable at the speed you want, then work the voltage down to find the lowest voltage the pc is stable with at your desired speed.

voltage = heat, so the lower you can get your voltages and stay stable, the lower the temps will be.

Thing is; if I start at the speed I want (i.e. 4Ghz) with a vcore of 1.4v I'm gonna crash through high temperatures (rather than a lack of voltage).

In that case would I knock the voltage down to see if I can get temperature down without starving the CPU of power?

 

[Freakbro]

In that case would I knock the voltage down to see if I can get temperature down without starving the CPU of power?

Yep

Im no expert but from the bit i've read around these forums, the 920 C0 is harder to get to 4.ghz anyway ie: needs more voltage than the D0 stepping.

So you might find it hard to get the temps/voltage/speed combo with the cooler you have, you can but try

though those temps you posted, even at idle , do seem very high - again i dont know whats normal for that chip...but it shouldnt be that much different at idle

At stock speed i would guess you should be in the range of 35-38 at idle?

So try redoing your heat sink and paste....less is more!

 

[RiGoRmOrTiS]

I would also be interested if anyone who has owned or still owns a C0 920 could tell me what their maximum acceptable overclock was on air cooling.

is there a huge realworld difference between 3.2Ghz and 4Ghz?

would 3.2Ghz bottleneck my SLI setup; whereas 4Ghz wouldn't?

(off home soon to fiddle with my volts and clocks!)

 

[RiGoRmOrTiS]

ok!. update on the situation..

I've not had a chance to re-sit my cooler yet; but here is what I've managed playing around with the voltages.

First of all, 4Ghz was a no-go; would blue screen after 30 seconds on my first attempt with Prime95. So I decided to aim lower; 3.8Ghz (190x20) with Turbo off.

I tried at 1.40v first and it shot straight to high 90's; even touching 101 within 5-10 seconds; I quickly ended the stress test and knocked voltage down to 1.35. Much better this time; took 2 mins before it started hitting mid 90's. However I stopped it at this point since I'm not happy with it in the 90's. I started doing small decrements one at a time; each time it was giving me longer and longer on Prime95 before hitting the 90's.

Long story short; the lowest I eventually took it to was 1.29v but that BSOD within 2 minutes while still at high 70's; so obviously not enough voltage. After further testing I found the lowest; stable vcore I could use at 3.8GHz is 1.31v.

I ran Prime95 for a full 30 minutes and the highest it got was 89c; averaging around 85-88c. Idle temperatures have also dropped on all my cores; before I was averaging 55-57 between all 4 cores; now 50 - 45 - 49 - 45. This is a big improvement and the PC is stable at 3.8Ghz. I know the temperatures are still a little high on load; but even a drop of 7-8c would bring things within an acceptable range (imo). I expect to get at least some of that from re-siting my heat sink (since I remember I bathed the CPU in thermal paste when I originally built the system and couldn't be bothered to clean it and do it again.

Does this sound good to you folks or am I missing something obvious here?

 

[Freakbro]

Sounds ok

yea if you swamped the cpu in paste that wont help at all. The 2 suggested methods are a rice sized grain in the centre or a thin line in the middle (see arctic silvers site for the size) and in both methods just put the cooler on and let the pressure spread it out.

Make sure you lean everything up well (non lint cloth etc) google the best way to do it.

Also, saying your pc is "stable" is a relative term. People have lots of different definitions of stable, but running Prime for 30mins usually isnt it

Ive had prime fail after 4 hrs while testing, but it all depends what your after. If you play games and find it freezes or bsods then you might need to do some more tweaking with voltages and Prime

 

[RiGoRmOrTiS]

Sounds ok

yea if you swamped the cpu in paste that wont help at all. The 2 suggested methods are a rice sized grain in the centre or a thin line in the middle (see arctic silvers site for the size) and in both methods just put the cooler on and let the pressure spread it out.

Yeah I know; but I was somewhat over zealous the last time.

Also, saying your pc is "stable" is a relative term. People have lots of different definitions of stable, but running Prime for 30mins usually isnt it

Well considering how quickly I could get things to fail or overheat at other voltages I took a "good enough approach". Ran a few games as well without issue. But of course I'll keep an eye on it. I figured 30 mins was enough since as you'd think a lack of voltage would show up within 30 mins of push a CPU to 100%?

Ive had prime fail after 4 hrs while testing, but it all depends what your after. If you play games and find it freezes or bsods then you might need to do some more tweaking with voltages and Prime

in what way? overheat? blue screen at normal temp?

 

[Freakbro]

Ive had prime fail after 4 hrs while testing, but it all depends what your after. If you play games and find it freezes or bsods then you might need to do some more tweaking with voltages and Prime

in what way? overheat? blue screen at normal temp?

Its bsod after 2 hrs on one test run and on another after 4hrs one of the worker threads on prime 95 failed. No change in temps, it just shows the cpu isnt "stable"

I ran mine for 16hrs on prime and called that stable, but thats just me

If you dont get any problems in games then its stable enough for you.

 

[RiGoRmOrTiS]

Its bsod after 2 hrs on one test run and on another after 4hrs one of the worker threads on prime 95 failed. No change in temps, it just shows the cpu isnt "stable"

I ran mine for 16hrs on prime and called that stable, but thats just me

If you dont get any problems in games then its stable enough for you.

fair enough well thanks for all the help. I'm making progress; hope re-sitting the heatsink gives me the benefits I hope; then all is good. If not I might get a new cooler. any that you would say is best? I was thinking the Prolimatech Megahalems with 2 120mm's; assuming I can fit it in without removing any DIMMs.