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Wierd CPU Heat Issue

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September 22, 2009 2:21:58 PM

So I have a Kuma 7750 on a ASRock 780 FullHD board with a small Coolermaster heatsink http://www.newegg.com/Product/Product.aspx?Item=N82E168... and I have the wierdest heat readings.

My CPU is overclocked to 3.1ghz @1.31v, which according to Outervision's PSU calculator puts it's TDP at 131w, high, I know, but not crazy high.

I get the wierdest temperature readings however, Speedfan reports my CPU temperature as around 58*C idle and 62-64 under medium loads like WoW (1 core @ 95% other at 50%) but it reports my core temperatures in the high 30s at idle, going up to the high 40s under load, and these temperatures are consistant with what AoD reports for the cores.

Is it even possible for the CPU temperature to be higher than the core temp? I thought the cores were supposed to be the big heat generating bits of a processor. Is one of my thermal diodes messed up? if not, what's generating all that heat? the L3? If I know the CPU Diode is reporting 20* too high, then I can deal with it by just programming the motherboard to keep the fan on low until it hits what it thinks is 65*c, and just paying attention to my core temps, but the uncertanty of this worries me.

Any and all help would be appricieated. (and yes, I know it's a crappy processor, but it was a $60 processor, with a $25 off newegg combo deal with a corsair PSU when I bought it. :kaola:  )

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a b à CPUs
September 22, 2009 5:47:11 PM

#1, its not a crappy cpu. i have one overclocked to 3.21 MHz on stock voltage.
check the temps with everest, real temps or hardware monitor, just to see what they will show. sometimes u need to manually set some setting in speedfan (like tjmax etc) in order to have precise readings.
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September 24, 2009 4:37:23 AM

I apologise about the "crappy CPU"comment. I just wanted to get rid of any "get a PII/C2D/i7" comments before they started. the 7750 is more than enough CPU for what I do (Civ4, WoW, HD movies with the 4870 etc.-and all at a price that no Intel CPU can come close to matching) Anyway, I tried Everest, and it reports the same temps (give or take a degree) This leads me to conclude that the software that i'm using to monitor the temps isn't an issue as 3 sources all report the same temperatures. I'm still left wondering if it's possible for the CPU temp. to be higher than the core temp.
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a b à CPUs
September 24, 2009 9:40:08 AM

Try Realtemp... works better for AMD.
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September 24, 2009 12:58:04 PM

amdfangirl said:
Try Realtemp... works better for AMD.



Really? Realtemp says "error: this processor isn't supported" Anyway, at this point I'm pretty sure that the issue isn't the software that I'm using to read the sensors, because 3 different places all report the same thing, including the BIOS for the CPU temp, and an APP distributed by AMD for the Core temps. I'm wondering if my "CPU" sensor is just mis-calibrated because Idling around 60* seems crazy high , and it's also about 15* higher than the cores, which I thought were the hottest part of a CPU. Also, when I touch the heatpipe on the heatsink right where it comes away from the CPU it's too hot to hold my hand there for very long, but not "ouch" hot.

Can anyone tell me if it is even possible for another part of the CPU to be hotter than the cores in a modern processor design?
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a b à CPUs
September 24, 2009 1:46:56 PM

Yes, it is possible.
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September 24, 2009 4:11:44 PM

amdfangirl said:
Yes, it is possible.



Really? Theoretically possible or functionally plausable?
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Best solution

a b à CPUs
September 24, 2009 6:50:38 PM

CPU temperature is always lower than Core temperatures when a balanced load is applied to all cores, such as Prime95 Small FFT's. The only exception is during an unbalanced load, when it's possible for CPU temperature to be slightly higher than an individual Core that's processing the lightest workload.

As the author of the Core i7 and Core 2 Temperature Guide, I don't typically offer comments on AMD processor temperatures, however, the sensors function similarly to their Intel counterparts. The hottest regions within the entire processor package is at the source, which is the cores. Your BIOS is simply miscoded, which occurs all too often, since BIOS programmers must write code for every possible processor variant for a given socket.

There's a 5c gradient between CPU temperature and Core temperature on i7's and Core 2's, and ~ 7c on AMD processors. Although the specifications differ slightly, if you click on the link in my signature, it's explained in detail. Your erroneous CPU temperature can be corrected in SpeedFan by reviewing Section 11 in my Guide.

Hope this helps,

Comp :sol: 
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a b à CPUs
September 25, 2009 6:28:29 AM

^ What he said

Computronix is the king of thermals :p 
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September 28, 2009 12:50:18 AM

CompuTronix said:
CPU temperature is always lower than Core temperatures when a balanced load is applied to all cores, such as Prime95 Small FFT's. The only exception is during an unbalanced load, when it's possible for CPU temperature to be slightly higher than an individual Core that's processing the lightest workload.

As the author of the Core i7 and Core 2 Temperature Guide, I don't typically offer comments on AMD processor temperatures, however, the sensors function similarly to their Intel counterparts. The hottest regions whithin the entire processor package is at the source, which is the cores. Your BIOS is simply miscoded, which occurs all too often, since BIOS programmers must write code for every possible processor variant for a given socket.

There's a 5c gradient between CPU temperature and Core temperature on i7's and Core 2's, and ~ 7c on AMD processors. Although the specifications differ slightly, if you click on the link in my signature, it's explained in detail. Your erroneous CPU temperature can be corrected in SpeedFan by reviewing Section 11 in my Guide.

Hope this helps,

Comp :sol: 



Thank you.
It feels good to have my gut feelings confirmed, And this heat issue actually prevented me from going further with my overclocking (and I even actually scaled back on those un-A/C'd 90* days) I could never explain why this was happening, and I always wondered what the reason was. I didn't look at that guide beforehand, because if was for intel processors, but it is impressively comprehensive. It's always good to have somebody expand my knowledge, I love to know the "why". Unfortunately, all to often people just give curt answers, like confirming that it is possible for the CPU temp. to be higher than the core temp, without explaining the situations where that would be possible, or saying that a 20*c difference is not a likely occurrence.

Thanks again
--A guy who hasn't given Intel a dime since 1998
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a b à CPUs
October 1, 2009 7:38:59 AM

I humbly thank you so very much for the "Best Answer" honors. :D 

I'm just glad I could help, and that's reward enough for me. I have considered expanding my Guide to the AMD and Intel Temperature Guide, however, as the Intel temperature threads keep me quite busy here at Tom's, I don't wish to take on the additional workload of the AMD temperature threads, unless I'm certain that I can do justice to all enthusiasts from both camps.

I'm no fanboy; I just run the fastest technology. As a Flight Simulator enthusiast, which is the most CPU bound title you can run, I've build my rigs around whatever processor has the most overclockable horsepower, regardless of the corporate logo. Most of my rigs were AMD until Intel released the Core 2. My sweetest AMD rig was my Opty 170 @ 3.0 Ghz. :love:  You can all rest assured that if AMD regains the CPU performance crown, my Flight Sim rigs will have an AMD under the cooler.

Thanks again for the honors,

Comp :sol: 
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