CPU faulty temp sensor?

[Jordan_l123]

So today I turned my PC on and went to play a game, after a while when playing a CPU intensive game I noticed I couldn't hear the CPU fan speed up. I opened speedfan and my "temp3" which I believe is my overall CPU temp was at -128degrees celcius. But the cores were between 62 celcius and 50 celcius. normally they are much cooler when playing this game.

Also I took some temps in speedfan at idle and the fan was at the same speed as when in the game, I am pretty sure that this would mean there is a faulty temp sensor in the CPU. If I were to render a video or image or convert a video it would get pretty hot! So what I want to know is what can be done about it? I have a feeling I will have to send it back as it is still under warrenty, or is there somthing else I could do. I have googled about but can't find an answer, so I would like your advice please on what I should do, or what you you think has caused this! I have attatched some screenshots for you as well. (Im using the stock Intel heatsink on an i5 750 by the way)

EDIT:

Thanks, Jordan

 

[Desolation]

have you dusted you computer lately also temp 3 is probably just a dummy sensor and is not used

 

[Jordan_l123]

Well, I dusted it like a month ago, and all has been fine up untill today. Also that Temp3 sensor used to rise with the CPU when under load. Also as the CPU fan doesn't rise when the CPU gets hot it seems like the sensor is somthing important. It's a Gigabyte GA P55 USB3 board if that helps, thanks!

 

[Desolation]

hmm im not really to up on Intel motherboards. you'll have to wait till one of the Intel guys chimes in

 

[Jordan_l123]

Ok, I appreciate your help anyway

 

[MindoverMaster]

You rang?

Try using HWMonitor, just to compare. Post us a scrrenshot.

Also, the stock heatsink can not cool well while under a heavy load. I would suggest getting an after-market one.
Cheap, but good: Newegg.com - ARCTIC COOLING Freezer 7 Pro Rev.2 92mm Fluid Dynamic CPU Cooler

My i5 760 hits around 70 when stressed. And that is at an overclock.

 

[Jordan_l123]

Ok here is a screenshot with HWMonitor and Speedfan side by side, after reeboting my computer, it seems to have gone up to about minus 72 celcius.

In HWMonitor it doesn't show that temp, however I still feel it is important, as I was converting a video earlier and the cores got up to ~70 celcius in a conversion that took under a minute and the fan was still at ~1110RPM, where it would usually go to near 2000RPM.

You are right, I should really get an aftermarket heatsink, but I have found the Intel one to be alright for my needs, and for a stock heatsink.

Thanks, Jordan

 

[MindoverMaster]

I think Temp3 is your Northbridge. That is known to be hot while ticking numbers away.

 

[Jordan_l123]

It could very well be the Northbridge, is there any way to find out for certian? However I still have my doubts, is it possible for these sensors to become uncalibrated? I ask this because under load, all the cores got up to between 70 and 80 celcius and Temp3 rose from minus 74 to minus 34, so it could be (as you say) the northbridge warming up, but and I know I keep banging on about this but the CPU fan still didn't ramp up from idle, even when the cores were touching 80. So as the CPU fan should only ramp up when the CPU gets hot, the CPU temp reading the motherboard is going by I suspect is this Temp3, and obviousley when it rises to a certian value, the fans ramp up, then when it gets hotter it ramps up some more. But because its always reading a negative number, the motherboard thinks the CPU is cold, so puts the fan on very low. I might Email Intel or Gigabyte about it and see if they know any more about it. What do you think to my theory?

I really apreciate your help everyone,

Jordan

 

[MindoverMaster]

Do you have the fan set to system controlled? That'd be in BIOS. I know this, because on one of my systems, it runs on full blast all the time. But if I set it to a certain percentage at so temp, it quiets down.

Do you have a 3 or 4-pin fan for CPU?