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CPU temp lower than ambient?

Last response: in CPUs
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December 29, 2011 6:36:24 AM

Hi, I recently had a problem with my motherboard and RMA'd it for a new one. So the new one came, and I didn't have new thermal paste so I had to put the CPU cooler back on with dried out paste. I had temperatures idle at 50-60c and Prime95 go over 99c. Playing a game like League of Legends went up to as much as 92c. So I cleaned out all the thermal paste and just left it clean. It idled at 40 but still went over 90c on Prime95. I decided I would get a new cooler and thermal paste. I decided on Artic Silver AA and the Coolermaster Hyper 212 Evo. After installing the new cooler and new paste, I'm getting temperature readings of as low as 14c. My thermostats for the house says the ambient is at least 20c. What is the problem? How is it possible that my CPU temp is 6c below ambient?


The programs I'm using are Core Temp and Speedfan.
I'm using an MSI P55M-GD41 Motherboard with an i7 860.

More about : cpu temp lower ambient

December 29, 2011 6:51:12 AM

Any modern CPU has no problem running at 90c for a short amount of time man. Any current CPU will slow down after 99c to avoid damaging itself. And no, it still perform very well.
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a c 185 à CPUs
December 29, 2011 6:56:56 AM

make sure you get new thermal paste before using your computer again....
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December 29, 2011 7:00:41 AM

read my post again, I already have the new thermal paste. I want to know why I am getting temp reading lower than my ambient.
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a c 202 à CPUs
December 29, 2011 7:11:35 AM

sk718 said:
Any modern CPU has no problem running at 90c for a short amount of time man. Any current CPU will slow down after 99c to avoid damaging itself. And no, it still perform very well.


You ask advice then you argue with people who work with these things on a daily basis?
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December 29, 2011 7:43:25 AM

Novuake said:
You ask advice then you argue with people who work with these things on a daily basis?



Maybe you should read my whole post instead of the first line and replying something that has nothing to do with my problem.
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a c 202 à CPUs
December 29, 2011 8:43:29 AM

sk718 said:
Maybe you should read my whole post instead of the first line and replying something that has nothing to do with my problem.


Your problem is a damages chip/motherboard. You can not expect reliable temp readings from damaged parts.
Inaccurate temps are the first signs of trouble.
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a c 103 à CPUs
December 29, 2011 12:34:16 PM

http://www.cpuid.com/softwares/hwmonitor.html

Run this and see what you get.

Its the full load temperature that you should be worried about, although I have read a few postings about i7 have broken sensors, you could RMA to Intel, but don't tell them about running without heat paste or they will void RMA.
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a c 172 à CPUs
December 29, 2011 12:43:06 PM

You new thermal compound must be magic. :bounce: 
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a c 202 à CPUs
December 29, 2011 12:55:17 PM

Thank you. Some backup...
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December 29, 2011 1:00:40 PM

i done the same to my old athlon and it popped with an almighty bang.

I am suprised it still works TBH. Very Lucky.

Get it checked via some apps as described above. You might just be ok.
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December 29, 2011 4:42:44 PM

Novuake said:
Your problem is a damages chip/motherboard. You can not expect reliable temp readings from damaged parts.
Inaccurate temps are the first signs of trouble.


I'm 100% sure there is nothing damaged. Idle CPU voltage is 0.89 while full load is 1.18.


Min temp is 14c after overnight idle, Max temp is 53c on Prime95
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a b à CPUs
December 29, 2011 5:03:59 PM

With modern thermal regulation and speed step the computer can do 2 things to control temp. It can back down the FSB and Multiplier and the VRM can back down the v-core. I think its extremely unlikely that you did any damage, however when it comes to computers anything is possible.

More likely Core temp is wacked out and not reading correctly or the onchip temperature sensor is defective.

Check the temp in the mother board bios. It should idle around room temp while in the bios cause it is not doing any work. If it is lower than room temp the sensor or bios is wacked. You can try update the mobo bios. If the temp seems normal here then try hwmonitor in windows.

If the CPU sensor is defective best bet is to just live with it. Core temp should show you the temp of all 4 cores. Its unlikely that all 4 sensors are wacked so go by the highest one.
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a b à CPUs
December 29, 2011 5:09:32 PM

Novuake said:
Your problem is a damages chip/motherboard. You can not expect reliable temp readings from damaged parts.
Inaccurate temps are the first signs of trouble.

Novuake said:
You ask advice then you argue with people who work with these things on a daily basis?



You can’t be sure of anything in situations like this. Your comment is awfully arrogant. One thing I have learned in my 15 years of building and supporting PCs is anything is possible, and just when you are sure you know what the problem is something impossible happens to prove you wrong.

That said there is a pretty good chance that board and or chip messed up, but I would bet its fine.
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a c 82 à CPUs
December 29, 2011 7:47:27 PM

cpu sensors have trouble detecting low temperatures, the lower the temperature, the less accurate they are. Go by the full load temp, disregard the idle temp if its that low. Something to try would be to update your motherboard BIOS with the latest from your manufacturers website. This can often fix temp monitoring issues. Even just hard resetting the bios to factory defaults can fix odd issues like this. I've seen cpu's report 128C and flashed to new bios and it was fine. Have had fans running at max speed, no matter what settings, hard reset the BIOS, fixed. So try that, it might/might not work, but its worth a try.
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