Bios Shows Wildly Flucuating NEGATIVE Temps


Mar 3, 2010
hi all,

first time posting and I am completely stumped.

About a week ago, the stock cpu fan on my secondary pc (click here for full specs starting making insane jet engine revving noises, constantly powering on and off no matter what was going on. i figured it was failing and went and bought myself a masscool aftermarket heatsink and fan. I took out the old cpu fan and replaced it with the new one and booted up the machine.

it ran well and quiet for about 25 minutes before the fan started going haywire again. i went to check out the bios and it was showing -45c/+242f and wildly fluctuating all over the place. I figured it had to do with the installation of the new heat sink so I started over, taking special special care on the work I was doing. booted back up and had the same problems. I checked the core's temps and everything seemed normal; they were showing 32c and 34c respectively.

now, after a few days of trail and error actions, other pieces of hardware are going wonky. today, it seemed as if the stock sound card failed. on another boot, it played sound. then after another, it was back out. mouse freezes up from time to time after a few minutes of basic computing. i am getting a floppy control error on every boot (for which i simply disabled the floppy device in BIOS). nothing I do seems to work; no application of thermal grease seems to solve the problem. I am truly stumped.

could the cpu temp sensor be failing? I honestly don't even know if that is a feasable problem on a computer nor do i even know what one looks like.

any help would be truly appreciated. I hate giving up and I have exhausted every idea I can think of.

ps. it should be noted that this machine is running ubuntu jaunty.

Have you checked the "hardware monitor" or "pc health" sections in the bios? Either name should include some fan settings. I calibrate mine if this option is presented, then lower the numbers more to keep the noise down. 2000-2500 rpms is plenty to keep things cool, especially in an air conditioned room. To enter the board bios, press "del" or one of the f keys listed on the post screen. I've always had problems with sound cards sooner or later, so I only use the onboard sound.


Mar 3, 2010

Thanks for responding.

To answer your question, I have. Any change I make in Bios has little or no effect to what is going on with the fan.

Remember, the cpu temp goes from 37c to -48c in a manner of a minute. It is almost as if the fan is constantly changing speeds. it is honestly the most insane thing I have ever heard.

I just took the heatsink back off, cleaned it and then reapplied the thermal grease. the heatsink is in there fine, firmly against the cpu. in bios on this most recent boot, bios freezes when i attempt to enter the "PC health" screen.

Here's some copy and pasted data from my terminal:

Adapter: ISA adapter
VCore: +1.17 V (min = +0.00 V, max = +1.74 V)
in1: +9.72 V (min = +7.66 V, max = +7.97 V) ALARM
AVCC: +3.28 V (min = +3.17 V, max = +2.05 V) ALARM
3VCC: +3.28 V (min = +3.63 V, max = +0.34 V) ALARM
in4: +1.62 V (min = +0.26 V, max = +0.10 V) ALARM
in5: +1.81 V (min = +0.74 V, max = +1.05 V) ALARM
in6: +5.89 V (min = +0.38 V, max = +2.07 V) ALARM
VSB: +3.20 V (min = +1.60 V, max = +0.03 V) ALARM
VBAT: +3.17 V (min = +0.11 V, max = +2.18 V) ALARM
Case Fan: 0 RPM (min = 21093 RPM, div = 4) ALARM
CPU Fan: 0 RPM (min = 21093 RPM, div = 4) ALARM
Aux Fan: 0 RPM (min = 21093 RPM, div = 4) ALARM
fan4: 0 RPM (min = 0 RPM, div = 2) ALARM
fan5: 0 RPM (min = 37500 RPM, div = 2) ALARM
Sys Temp: +35.0°C (high = +18.0°C, hyst = +99.0°C) sensor = thermistor
CPU Temp: -128.0°C (high = +80.0°C, hyst = +75.0°C) sensor = diode
AUX Temp: +8.5°C (high = +80.0°C, hyst = +75.0°C) sensor = thermistor
cpu0_vid: +0.000 V

Adapter: ISA adapter
Core 0: +39.0°C (high = +86.0°C, crit = +100.0°C)

Adapter: ISA adapter
Core 1: +36.0°C (high = +86.0°C, crit = +100.0°C)

bios, when last checked, was similar.


Mar 12, 2010
I think I have the same problem. I was thinking some sensors on the board are jacked up. This causes my computer to shut down after a minute of turning it on. CPU temp is at 85C, and each one of my cores is at like -40C. You find a solution yet?? THinkin about tryin to change the power supply first since my friend is letting me borrow it. If that doesn't do it, I'm gonna probably change the motherboard?? Man I'm stumped