CPU What the....

so i just got home from work and fired my computer up. after booting into windows, i noticed my fans werent running. my fans are all controlled through the CPU header via a fan controller i built, but the fan controller seems to be working fine.

so i restarted the computer to see if it would fix itself, and popped into the bios to check things out. the bios is reporting my CPU temp as -10 degrees celcius. the motherboard is supposed to control the fans based on temp, so i assume thats why they are off since it thinks the computer is below freezing.

in windows, easytune6 says my CPU is pegged at 100C and it wont let me take control of the fans through software. realtemp and CPU tweaker both report normal-ish idling temps in the high 30's. im inclined to believe the latter 2 since i dont feel that much heat coming out of the system.

what could be causing the motherboard to read the wrong temperature from the CPU? has the temp sensor inside the CPU gone kaput on me?

as a side note: i guess my system runs completely passive (ex. GPU) without much fuss

 

Service pack 1?

Be careful, someone lost their laptop to service pack 1, but it doesn't explain the bios.

Maybe the sensor has gone, but then i presume the one you use in windows is using a different sensor. What does coretemp say?

 

yes, but that shouldnt make a difference as the fans are all controlled via hardware. plus it just started doing this today, ive had SP1 for a while.

also, just restarted so i could disabled fan control (fans running at max), and the CPU was reported at -40C this time (before saving to BIOS, so the fans were still off at that point).

 

I know the Asus R3E had a similar issue with stuck/negative CPU temps, perhaps something similar is happening with your gigabyte board?
Check for BIOS updates, and it might be worth it to clear the CMOS too.

 

This was the thing, I thought it was all controlled by hardware but apparently windows does have some control via the power settings. What does Coretemp say? I'd use as many different sensors to check what is still working.

 

I'd 2nd a CMOS clear or update the BIOS. It should clear any errors if it was working fine before!

 

thanks for the suggestion pheonix. ive been googling and it seems that there might be a small issue with this with GB p55 boards. i havnt found a solution yet, but the general consensus is that its a BIOS issue. its just weird that it started doing it suddenly.

another suggestion on GB's forum was possibly something to do with the mains supply. i did recently purchase a new UPS to plug my machines into. although it hasnt effected the sandy bridge rig, maybe its messing with my 750?

 

had the computer off for a bit to rearrange my monitors. turned it back on and the problem has fixed itself for the time being.

it was weird, every time i entered the BIOS, the temp was 10 degrees lower. it got to -90C.

will report if i find a permanent cure. i wont flash the BIOS unless im reasonably certain it will fix the problem.

 

If it happens again, reset the BIOS (take out battery or use reset pins, etc) and see if that fixes it, even temporariyl. That would show a corrupt BIOS (i.e. BIOS file corrupting readings over the time it hasnt been reset)

 

Most GB boards have dual BIOS chips. If your BIOS is corrupt, you should be able to copy over the backup.

 

i thought the dual BIOS was more for cases where the primary BIOS is so corrupt as to cause the board to not boot. if i need to reflash the BIOS, wouldnt doing so in windows be the same as recovering it with dual BIOS?

ive never had to mess with dual BIOS before, i really dont know how it works.

 

I had this problem with my Gigabyte board, although mine never got down to -90 I found updating the BIOS sorted it out. Although I would try resetting the BIOS as Confusis said first.

 

fired the computer up this morning and its still OK. i have to wait for the next time it acts up to do anything or else who knows if what i try actually does anything.

i will try resetting the BIOS, and if that doesnt work, ill reflash it to the most current. from what i can gather, gigabytes technical team cannot duplicate the problem in their lab, so they are taking the stance that the problem does not exist. thanks gigabyte