What temperature would you fell is good for a prime95 OC run?

Locut0s

Lifer
Nov 28, 2001
22,205
43
91
Ok I've just got my i7 970 from the Intel Retail Edge program and couldn't be happier. This thing is very noticeably faster than my 920. But I thought I'd have some fun and OC it to 4Ghz. I have a noctua D14 anyway so I thought it should be able to do that fine. Well I had no problem hitting 4Ghz without even touching any of the voltages, just upped the BCLK to 166. Ran Prime 95 for 10 hours and all was stable. However my temps according to Core temp were around the 85-90 range which is too high in my mind. At idle I'm seeing 35-40C range. I would think that a Noctua D14 would perform better than this? I know 100% that it is seated properly as I have played with it several times and this is the best seating I've managed to get. I MAY not have the fans in my case positioned properly though. How much of a difference can this make? I have a Corsair 800D case with 1 120mm fan at the back as outtake (the D14 also blows it's air right at this fan). 1 Fan in the front as intake and 2 fans on top as intakes. I'm thinking of switching it to all intakes and having 3 fans on the top as output.

I had a similar issue with OCing my 920 so I don't think it's the CPU.
 
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Rifter

Lifer
Oct 9, 1999
11,522
751
126
When i was testing my 930@4.2Ghz in the summer with 30-35c Ambient temps it was hitting 90C give or take 5c after 12 hours of prime.

Now with ambients in the 10-15c range it stays below 80C, usually closer to 75C. I also have a NH-D14. BTW it ran fine all summer so i wouldnt worry too much about hitting 90c, im pretty sure intel specs say either 100c or 105C is the max temp.
 

eelw

Lifer
Dec 4, 1999
10,228
5,343
136
My 970 is OCed to 4.6 and that only hits high 80s on my Noctua U12 and it idles in the low 20s. I can get it to 4.8, but isn't stable with temps reaching 99C. So I'll leave it at 4.6.
 

Locut0s

Lifer
Nov 28, 2001
22,205
43
91
My 970 is OCed to 4.6 and that only hits high 80s on my Noctua U12 and it idles in the low 20s. I can get it to 4.8, but isn't stable with temps reaching 99C. So I'll leave it at 4.6.

The U12 shouldn't be heads and tails above the D14. Wonder if I have a bad HSF or if it's the case fan setup?
 

ZipSpeed

Golden Member
Aug 13, 2007
1,302
169
106
Ok I've just got my i7 970 from the Intel Retail Edge program and couldn't be happier. This thing is very noticeably faster than my 920. But I thought I'd have some fun and OC it to 4Ghz. I have a noctua D14 anyway so I thought it should be able to do that fine. Well I had no problem hitting 4Ghz without even touching any of the voltages, just upped the BCLK to 166. Ran Prime 95 for 10 hours and all was stable. However my temps according to Core temp were around the 85-90 range which is too high in my mind. At idle I'm seeing 35-40C range. I would think that a Noctua D14 would perform better than this? I know 100% that it is seated properly as I have played with it several times and this is the best seating I've managed to get. I MAY not have the fans in my case positioned properly though. How much of a difference can this make? I have a Corsair 800D case with 1 120mm fan at the back as outtake (the D14 also blows it's air right at this fan). 1 Fan in the front as intake and 2 fans on top as intakes. I'm thinking of switching it to all intakes and having 3 fans on the top as output.

I had a similar issue with OCing my 920 so I don't think it's the CPU.

Is your CPU voltage set at auto? If so, it's possible your motherboard is overvolting the CPU at 4 GHz. Getting that voltage down to the minimum needed for your overclock is important in controlling temperature. My i7 970 only requires 1.2V at 4 GHz and I get upper 60s at full load.
 
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Sunny129

Diamond Member
Nov 14, 2000
4,823
6
81
I MAY not have the fans in my case positioned properly though. How much of a difference can this make? I have a Corsair 800D case with 1 120mm fan at the back as outtake (the D14 also blows it's air right at this fan). 1 Fan in the front as intake and 2 fans on top as intakes. I'm thinking of switching it to all intakes and having 3 fans on the top as output.

I had a similar issue with OCing my 920 so I don't think it's the CPU.
i would take a serious look at this possibility. if your case fans aren't set up for optimal cooling, there's a chance that hot air may be building up inside your case. the temperature of the air surrounding your CPU's HSF can heavily affect its ability to cool your CPU. the temperature of the surrounding air should obviously be cooler than the fins on your HSF. the smaller this temperature differential becomes, the less heat your HSF will be able to radiate away from your CPU. if the surrounding air temp eventually becomes equal to the temp of the HSF's fins, no heat will transfer from the HSF to the surrounding air OR vice versa. if the temperature of the surrounding air ever eclipses that of the fins on your HSF, then obviously the HSF will not radiate away the CPU's heat, but rather it will absorb the surrounding air's heat, thus heating your CPU further...not that i've ever seen case temps that high before, but that's how heat transfer generally works in theory.

you currently have 3 intake fans and 1 exhaust fan. without even considering the airflow characteristics of your case, it sounds to me like you're taking in more air than your 1 exhaust fan can evacuate...granted, i know other factors play into a fan's CFM like RPM and the # of blades (and not just the fan's diameter). but all other things being equal, and assuming your top fans are also 120mm, all that cold air being brought into the case may not be getting evacuated quickly enough by the 1 exhaust fan. in other words, if your fans are all approx. the same size, and the 3 intake fans are operating at similar RPM's, then the 1 exhaust fan has to be spinning ~3 times as fast to exhaust the air being brought in by the intake fans. remember, the more time that fresh cool air spends inside the case, the less fresh and cool it stays. you have to find a balance of fans that keeps cool air circulating through the case at a quick enough pace that it doesn't become stagnant and hot inside.

i think your idea of switching the rear fan to an intake fan and the top fans to exhaust fans is worth a try, but only if you can reverse the direction of the flow of the Noctua (or rotate it 180°) so that it isn't fighting against a rear intake fan. i'm pretty sure you can't rotate a Noctua unit 90° so that it blows up or down, but you might be able to rotate it 180° (or at least rotate the fans 180º) so that it flows the other way, that is, from back to front. this way, cool air comes in the back and cools the CPU right away. the Noctua then exhausts heated air toward the front of the case, where the top intake fans suck it up and out.

personally i think your top fans should have been exhaust fans in the first place. after all, hot air rises, so the top of the case is a natural location for exhaust fans. i'm assuming you don't have a place for a fan on the removable side of your case?
 

Locut0s

Lifer
Nov 28, 2001
22,205
43
91
Is your CPU voltage set at auto? If so, it's possible your motherboard is overvolting the CPU at 4 GHz. Getting that voltage down to the minimum needed for your overclock is important in controlling temperature. My i7 970 only requires 1.2V at 4 GHz and I get upper 60s at full load.

Thanks for the suggestion! I had them set all to auto and indeed the Vcore was set to 1.375 which is a bit on the high side. I turned it down to 1.2 and ran Prime again but my comp froze up after a few hours. I now have it uped to 1.275 and I'm running Prime again. So far so good. Temps are about 71C at the moment. If my comp remains stable through another 8 hours of Prime I'm going to keep it at this and them switch the fans around to see if I can lower the temps a little more.

All the other voltage I've left on auto so it's possible some of them are higher than they need to be as well I don't know. DRam is at 1.6 for example. I probably won't play with them much if I can avoid it though.
 

Locut0s

Lifer
Nov 28, 2001
22,205
43
91
i would take a serious look at this possibility. if your case fans aren't set up for optimal cooling, there's a chance that hot air may be building up inside your case. the temperature of the air surrounding your CPU's HSF can heavily affect its ability to cool your CPU. the temperature of the surrounding air should obviously be cooler than the fins on your HSF. the smaller this temperature differential becomes, the less heat your HSF will be able to radiate away from your CPU. if the surrounding air temp eventually becomes equal to the temp of the HSF's fins, no heat will transfer from the HSF to the surrounding air OR vice versa. if the temperature of the surrounding air ever eclipses that of the fins on your HSF, then obviously the HSF will not radiate away the CPU's heat, but rather it will absorb the surrounding air's heat, thus heating your CPU further...not that i've ever seen case temps that high before, but that's how heat transfer generally works in theory.

you currently have 3 intake fans and 1 exhaust fan. without even considering the airflow characteristics of your case, it sounds to me like you're taking in more air than your 1 exhaust fan can evacuate...granted, i know other factors play into a fan's CFM like RPM and the # of blades (and not just the fan's diameter). but all other things being equal, and assuming your top fans are also 120mm, all that cold air being brought into the case may not be getting evacuated quickly enough by the 1 exhaust fan. in other words, if your fans are all approx. the same size, and the 3 intake fans are operating at similar RPM's, then the 1 exhaust fan has to be spinning ~3 times as fast to exhaust the air being brought in by the intake fans. remember, the more time that fresh cool air spends inside the case, the less fresh and cool it stays. you have to find a balance of fans that keeps cool air circulating through the case at a quick enough pace that it doesn't become stagnant and hot inside.

i think your idea of switching the rear fan to an intake fan and the top fans to exhaust fans is worth a try, but only if you can reverse the direction of the flow of the Noctua (or rotate it 180°) so that it isn't fighting against a rear intake fan. i'm pretty sure you can't rotate a Noctua unit 90° so that it blows up or down, but you might be able to rotate it 180° (or at least rotate the fans 180º) so that it flows the other way, that is, from back to front. this way, cool air comes in the back and cools the CPU right away. the Noctua then exhausts heated air toward the front of the case, where the top intake fans suck it up and out.

personally i think your top fans should have been exhaust fans in the first place. after all, hot air rises, so the top of the case is a natural location for exhaust fans. i'm assuming you don't have a place for a fan on the removable side of your case?

Thanks! I'm currently playing with the VCore voltage as recommended above because I had it set to auto and it was at 1.375 and it seems I might be able to get away with 1.275 and that seems to have lowered temps. I will switch the fans after that.
 

Sunny129

Diamond Member
Nov 14, 2000
4,823
6
81
Thanks! I'm currently playing with the VCore voltage as recommended above because I had it set to auto and it was at 1.375 and it seems I might be able to get away with 1.275 and that seems to have lowered temps. I will switch the fans after that.
good. playing with voltages will definitely help. generally speaking, the more juice you send to your components, the hotter they'll run. but even if you get an appreciable drop in temps by playing with the voltages, based on your current fan configuration, i think you stand to drop temps even further by rearranging them...perhaps you'll see core/CPU temps drop by as much as an additional 5°C beyond what you can achieve by playing with voltages alone.

keep us posted on your results, as this info will be good for the entire community whether this experimentation is a success or not. good luck with everything. :)
 

ZipSpeed

Golden Member
Aug 13, 2007
1,302
169
106
Just as an addendum to my original post, after some exhaustive stability testing, my overclock at 4 GHz wasn't stable. Increasing the voltage added too much temperature to my liking so I backed it down to 3.9 GHz. Haven't had any failure yet so far. Fingers cross!
 

Locut0s

Lifer
Nov 28, 2001
22,205
43
91
Just as an addendum to my original post, after some exhaustive stability testing, my overclock at 4 GHz wasn't stable. Increasing the voltage added too much temperature to my liking so I backed it down to 3.9 GHz. Haven't had any failure yet so far. Fingers cross!

Well mine seems rock stable at 1.275 (about 11 hours of Prime95) and temps were in the 65-75 range which is acceptable. Thanks. Will look at the fans next.