P55 Mobos CPU sensor problem

[boglav]

To keep it simple: on 2 Gigabyte mobos running an I5 760 I got the same issue: after a random period of time, the CPU sensor on the motherboard gets "stuck" to an erroneus value (-35 to 0 degrees Celsius, read in BIOS). This causes the CPU FAN (which is set to auto in BIOS) to drop to the minimal RPM (~250 in my case on a Scythe Katana 3) thus producing a sensible increase of the CPU temp (the 4 cores reach up to 70 degrees under stress such as PRIME95). The core temps are read OK while this happens. Even after a system restart the issue persists, the only solution is to shut down the system, wait for a period of time and then restart.

After a research on Google I found similar posts about the problem:

http://forums.tweaktown.com/gigabyte/38345-ga-p55a-ud3-negative-cpu-temperature.html
http://www.overclock.net/intel-motherboards/664005-broken-thermal-sensor-gigabyte-p55-usb3.html

The issue appeared first on a GA-P55-USB3 (bios F8) which I replaced with a GA-P55a-UD3 (BIOS F9). Using the same configuration with an basic Intel H55 motherboard, no such problems issued.

Is there a solution for this issue besides setting the CPU fan to max RPM in BIOS (mine is very lous at 2700 RPM) or using a fan controlling SW? Are there any plans to fix this of future BIOS updates? 

[Dark Mantis]

It definitely seems like a BIOS issue so I would advise you to make sure that GGTS know about it and ask for a fix. There is obviously a problem with how the temps are being reported.

[boglav]

I just made a report to GGTS. I am intrigued though why there are such few reports on this problem. Am I just unlucky to get the same issue on 2 different mobos?
For testing resons I disabled C3/C6 state function in BIOS which is reported to be a fix for the short beeps/chirps emitted by this familiy of mobos. I used to get them with the USB3 version, the UD3 seems to be OK as far as that goes. Hopefully it might be a solution for the sensor issue as well. I will report on the problem later on.

[Dark Mantis]

To be honest there haven't been many reports of this problem on the forum at all. Maybe it would help if you could list all your hardware and we might be able to see some relationship between it and the trouble.

[boglav]

CPU Intel I5 760  2.80GHz + Cooler Scythe Katana 3
MOBO Gigabyte GA-P55A-UD3
Kingston Hyperx DDR3 2x 2GB 1333 CL7 9KHX1333C7D3K2/4GX)
HDD WD 640 GB WD6400 AAKS
Gygabyte Geforce 460 GTX OC 1 Gb 256 bit
PSU Seasonic 520W S12II-520

[Dark Mantis]

Wel the only thing that I would query is the PSU. It is good quality but a little underpowered.  I think it would be worth your while to see if you can get a good quality single 12V rail PSU of 650W + just to try. I know the theory of it all says that it should be enough but you would be suprised how many times we find this is the fault. In the motherboard manual it quotes 550W minimum for this board.

[boglav]

Unfortunately  cannot get a better PSU for testing since most of my friends own laptops and/or weaker PSU's and it's out of the question to buy another one, because this system was a big financial investment as it is.

[Dark Mantis]

No I do understand your problem, all this equiptment doesn't come cheap. I just wondered if there was a local computer shop that would let you try one if they thought they might get a sale out of it.

[Peteruk]

Its fine evga say 450W minimum (of course that would need to be a good PSU) 520W is fine.
http://www.evga.com/products/moreInfo.asp?pn=01G-P3-1365-TR&family=GeForce 400 Series Family&sw=

And with a less powerful card you need 550W no of course you don't its just Gigabyte covering their backs and for what to prove that their was nothing wrong with the PSU in the first place.     

[boglav]

Just found another guy with an identical problem on Gigabyte ex38-ds5 (BIOS reporting -88 degrees).
I'd take all other factors out of the question - it seems to be a Gigabyte problem or rather Gigabyte/Intel problem, just like the one with the short chirps/beeps, unless C3/C6 State is disabled in BIOS! I'm currently testing the same fix for this problem, hopefully it will work.

[Dark Mantis]

I don't know what you're moaning about people spend a fortune trying to get below freezing tempertures like that in their machines 

Only joking!

[boglav]

Funny, that was my first thought also

[Dark Mantis]

Just a shame it's not real You could do some major overclocking with temperatures like that.

[boglav]

I know this should sound weird, but can this problem be related to the building power source? I couldn't reproduce the issue at the shop where I bought the computer, and believe me we tried. Also it is not related to CPU load, in most cases in happened while browsing, etc. Just a thought..

[Dark Mantis]

Yes it's quite possible. What is your local mains power supply like there? Is it stable and clean? I used to live in Bulgaria and I know what some of these power supplies are like (even when they are on) I always used to run my system through a big UPS and still do.

Just another thought, if it happens when you are browsing have you tried disconnecting the modem/router from the computer?