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Crazy-low temp readings from i3 540

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April 21, 2010 10:09:58 PM

Hi everyone, I just built a PC with a Gigabyte GA-H55M-S2H motherboard and an i3 540 CPU. This is my first time using this processor and also my first time using an aftermarket HSF (Dynatron K987). I noticed something strange. The BIOS shows CPU temp as 20C, which is under ambient room temperature. Then, later, I ran Everest, CPUID Hardware Monitor, and Gigabyte's EasyTune 6. They all showed CPU as 15C, and the two cores as 21C and 26C.

So some questions:

1) Is it typical for the "CPU" reading to be higher than the individual cores?

2) Is it typical for one core to always be 3-6 degrees warmer than the other core?

3) What could cause the BIOS to show the CPU at 15 or 20 degrees when there's no way it could be that low? This CPU is pretty new, could Gigabyte just have a bug in the BIOS?

4) Prime95 elevated the cores to the mid/upper 50s. Is this good for this chip? Or rather, can anyone point me to a page that lists operating temperatures for this chip? I searched Intel's site for over an hour and couldn't find anything.

I'd be more concerned about it, but somehow it knows to speed up the CPU fan under load, despite the faulty temp values.

Thanks!
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April 21, 2010 10:32:54 PM

Quote:
What could cause the BIOS to show the CPU at 15 or 20 degrees when there's no way it could be that low? This CPU is pretty new, could Gigabyte just have a bug in the BIOS?


I think it could be that low or close to that low. The 540 is a low power/heat chip. And you said something about an aftermarket heatsink so maybe it is. I used to have a 65watt windsor X2 4600 that idled around 20-24c.

IF this was an I5 750 you would be right. But those tems appear within reason for that cpu.
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April 21, 2010 10:50:01 PM

FALC0N said:
I think it could be that low or close to that low. The 540 is a low power/heat chip. And you said something about an aftermarket heatsink so maybe it is. I used to have a 65watt windsor X2 4600 that idled around 20-24c.

Thanks for your reply. I'm not an expert on these things, but that doesn't sound right (my values, not necessarily yours). There's no way it was 59 degrees F in my room. More like 80F (~27C). From what I understand of the laws of thermodynamics, even the strongest fan in the world couldn't lower the temperature below room temperature. Also, Everest showed the "motherboard" temperature as 41C. I'm not sure what "motherboard" means, but if it's a general case temperature reading then it seems like the CPU would have to be higher than the 15-20 degrees just because the air in the case was higher.
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April 22, 2010 1:03:06 AM

The Gonif said:
Hi everyone, I just built a PC with a Gigabyte GA-H55M-S2H motherboard and an i3 540 CPU. This is my first time using this processor and also my first time using an aftermarket HSF (Dynatron K987). I noticed something strange. The BIOS shows CPU temp as 20C, which is under ambient room temperature. Then, later, I ran Everest, CPUID Hardware Monitor, and Gigabyte's EasyTune 6. They all showed CPU as 15C, and the two cores as 21C and 26C.

So some questions:

1) Is it typical for the "CPU" reading to be higher than the individual cores?

2) Is it typical for one core to always be 3-6 degrees warmer than the other core?

3) What could cause the BIOS to show the CPU at 15 or 20 degrees when there's no way it could be that low? This CPU is pretty new, could Gigabyte just have a bug in the BIOS?

4) Prime95 elevated the cores to the mid/upper 50s. Is this good for this chip? Or rather, can anyone point me to a page that lists operating temperatures for this chip? I searched Intel's site for over an hour and couldn't find anything.

I'd be more concerned about it, but somehow it knows to speed up the CPU fan under load, despite the faulty temp values.

Thanks!


It's common and quite popular for motherboard manufacturers to skew the temperature readings thus. I believe they think it makes them look better. I use REALTEMP, and the readings look much more realistic.

Whenever I do a CPU cooler review or an overclocking article, I get all kinds of readers claiming the temps are way too high, that they get lower temps with even less cooling, etc. I try not to argue too harshly because they don't know any better.

It's common for one core to be hotter than another, I typically see a 5C difference. Yours should probably be running around 5C over ambient at idle and 30C over ambient at full load, using the stock cooler.
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April 22, 2010 10:17:44 PM

Crashman said:
It's common and quite popular for motherboard manufacturers to skew the temperature readings thus. I believe they think it makes them look better.


Thank you for your reply. So what do you use to control your CPU fan? SpeedFan's temp readings are way off on this rig; do you just configure it with equally off values so it all works out?
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April 22, 2010 11:06:23 PM

The Gonif said:
Thank you for your reply. So what do you use to control your CPU fan? SpeedFan's temp readings are way off on this rig; do you just configure it with equally off values so it all works out?


I use BIOS for automatic fan speed control. For Core i7 processors, if BIOS kicks the fan to full speed at the 55C reading does it really matter if the actual temperature is 75C? These things can run for weeks or longer at continuous temps over 95C. Most of my BIOS' start ramping up the fan at a 35C reading and continuously increase it to max at a 55C reading.
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April 23, 2010 6:57:08 PM

Best answer selected by The Gonif.
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