Should I Worry About 7-8c Difference Between Cores?

lettuce · 1 Dec 2007 at 22:22

Have manage to OC my q6600 to 3.4Ghz now at 1.4250 volts for the moment, will get the volatge lower, on Abit IP35 Pro. Have been running Prime95 for about 2 hours now and Core Temp is giving me the following:

Core 0 = 65c
Core 1 = 63c
Core 2 = 57c
Core 3 = 57c

Abit uGuru is stating

CPU 49c
SYS 25c
PWM 77c

Should i really be worried at the difference in temps between the cores? Ive notice core 0 seems to stay solid at 65, where as the other cores readings shall flick between a reading really quickly ever few seconds. Also it UGuru is saying the CPU is at 49c how can each of the cores be hotter? Thanks

lettuce · 1 Dec 2007 at 22:56

Im glad to hear that, didnt fancy taking my mobo all out of the case again, thats an afternoon gone just there! Yeah i believe i using the quadcore prime95, this one here, ftp://mersenne.org/gimps/p95v254.zip ?? So when people post there OC achievements and they have the temp of the CPU, what program do they use to get this temp?

lettuce · 1 Dec 2007 at 22:56

PinkFloyd said:
Yes its quite normal, but have 2 cores both about 7 degrees hotter than the other too strikes me as something else causing it rather than coincidence

Every quad I've seen has had 3 cores about the same, one a bit off.

Have any suggestions??

lettuce · 1 Dec 2007 at 23:28

So im getting a reading from uGuru saying my CPU is 50c and thats with all 4 cores stressed. How likely is it in the normal world that all 4 cores are going to be stress to 100% at the same time?

lettuce · 1 Dec 2007 at 23:33

perox said:
Mine is the same, when idle there is about a 6-7 degrees difference between the cores, the gap closes though when I prime to about a 1 degree difference.

Seem strange how cores 0&1 are almost the same (about 2c difference) and then cores 2&3 are dead on the same as each other, but 7-8c cooler. And if im looking at the temps on my taskbar when Core temp is running, the first 2 cores are rock solid at 65 and 63, they havent changed from that for the last 10 minutes. Where the last 2 cores on my taskbar are constantly flicking really fast between 57c and 58c. Do these intel boards have the same sort of technology as cool n quite?

lettuce · 1 Dec 2007 at 23:36

sculptor said:
Its quite normal mate, one of my quads has a 10c difference between the hottest and coolest cores, Ive reseated the heatsink twice but its still the same.
My B3 chip is more or less dead even across all cores but all my GOs show a difference.
Try using "small FTs" in prime and it will even up the difference.

Yeah i did select small FTs for Prime95. Is there any options i need to tick with any of the option menus in Prime95??

lettuce · 2 Dec 2007 at 00:07

Errrr, no dont think i have, what does that do??

lettuce · 2 Dec 2007 at 00:35

Ok done so. Im think more and more that i might have my heatsink (Thermalright Ultra-120 Extreme) slightly off center from the CPU? As it has a large base you cant actual see the cpu at all once you have it hovering over the CPU. That might suggest why cores 0&1 are about 6-8c hotter than cores 2&3 maybe the heatsink is cover cores 2&3 more hence why they are colder?? What position are the cores on the cpu?

I just stop prime95 now, and cores 2&3 seemed to cool down to there ideal temp a lot quicker than cores 0&2, they are now sat at

Core 0 = 38
Core 1 = 35
Core 2 = 30
Core 3 = 30

Does my theroy hold any water, would it be worth clean up the cpu and reseating the heatsink again. The way i applied the thermal paste last time was with clinfilm over my fore finger and just added a pea sized drop of thermal paste on the center of the cpu, and smeared it all over the cpu until it was a fine layer. This time i may add thermal paste to the heatsink and do the same on that

lettuce · 2 Dec 2007 at 10:42

So you think its a good idea to stick thermal paste on both the cpu and heatsink?

lettuce · 2 Dec 2007 at 11:02

Well i did lap the Thermalright as it was very slightly concaved, i lapped it which brought up the copper on the underside of the base of the thermalright, after this i held it up to a light with a right angle and you could only just see light around edges of the base of the heatsink, but as the base of the heatsink is so much larger than the surface area of the cpu i wasnt too concered about this??

I inspected the same on the cpu, but there was less than a mm of light getting through when i tried it with the right angle, i didnt bother lapping that (plus i was too chicken to lap the cpu) as i thought a layer of thermal paste would fill what little gaps there was

lettuce · 2 Dec 2007 at 11:10

young said:
use something like a credit card, that way you can get a nice even layer of it

So you wouldnt recommended Arctic way of doing it, by squeezing a horizontal line cross the center of the cpu and just applying the heatsink to the cpu?

lettuce · 2 Dec 2007 at 11:51

Ive still got almost a whole tube of Artic Sliver left, i only put a pea size on the cpu and that all ive used of it, so i should have plenty. Think ill use the same method as last time (spreading it about) but this time ill also put some on the heatsink too

lettuce · 2 Dec 2007 at 17:24

In the end i decided to lap the CPU, while i had the pc apart, took about 15-20 in total, went from 200, 300, and then 600 grit paper, didnt bother going for the mirror look some people do though. Applied the paste in the same way i did before but this time with a little less paste, smaller than a pea but bigger than a grain of rich. Now after 20 minutes of Prime95, Core Temp is giving me the following reads:

Core 0 59
Core 1 58
Core 2 51
Core 3 51

What are the odd of actually lapping a cpu, re seating it again and getting more or less the same readings?? Cores 0&1 are 1c cooler, where as Cores 2&3 are about 3c cooler. This could even been down to the temp of my room now. But over all the differences between the hottest and coldest have stayed the same. Im guessing im never going to get all cores to be around the same temp

lettuce · 2 Dec 2007 at 17:43

I lapped my Heatsink when i first installed it, didnt have the balls to do my cpu then, plus didnt know if it worked as didnt try it out before, so though its best not too. Thats an intresting thing you bring up there about the heatsink and fan actually. I have one of those Antec 900 Gaming case....ill just take a pic actually be easy to show you

Now it has that big arse fan on the roof of the case which it really close to my heatsink so you would think that that side of the heatsink would get cooler than the other side?, as the way the mobo is oriented it places cores2&3 on the right hand side of the heat sink which is where that fan is. Maybe ill try discounnection that fan and see what happens to the temps??

lettuce · 4 Dec 2007 at 19:47

young said:
What might be a good idea is to put the fan on the otherside of the heatsink from what the picture shows. having two fans next to each other is pointless

Did as you suggested and placed the heatsink fan on the otherside, and it increased my core temps by about 6-7c. So have now placed it back and temps are now down again. Im guessing as the fan was right next to the ram that probably produced a bit of heat??