CPU Temp Sensor Jumping from 39C to 112C

[Phenom_]

Hello everyone,

My System:
Xeon 1230V3 / ASUS Z87K / HD7950 / 8GB DDR3 1866 / 750W EVGA Supernova

Some days ago my pc started to refuse booting up with a warning "CPU Overtemperature". It is the "CPU Temp" sensor in particular, which showed 112C (Bios and AIDA64). I quickly realized that the sensor jumps from 39C straight to 112C within a second whenever the pc heats up a bit. I already reinstalled my CPU Cooler twice (Scythe Mugen or Intel Stockfan) and always see the same transition from 39C to 112C.

All other sensors are working normally, I see 35C idle on my cores/package temp and 74C under full load in LinX after many hours - the "CPU Temp" can be as high as 135C then. The whole system never crashes or throttles its clock, but it still refuses to boot unless I tell the bios to ignore the "CPU Temp" values.
So my question basically is: Is the "CPU Temp" sensor located on the processor itself, or on the motherboard and/or its socket? I wanted to sell this processor in order to upgrade to a newer platform, but i couldnt do that if its the culprit. And one last thing: At the same time the sensor started acting weird, my 4x USB front case ports stopped working.

Thank you for your help,
Phenom_

 

[Mchalo]

Generally its in the CPU and measures the temp on the heat spreader in the center

ps. If you were going to sell your processor to upgrade to a new platform wouldn't you also need to upgrade your mother board or are you getting one with the same socket?

 

[Phenom_]

Hey Mchalo,
Oh well I guess I shouldnt really sell the processor then - dont want to get in trouble with the new owner ;O On the internet there were various opinions regarding the location of the sensor, some people said its in the socket of the motherboard. Unfortunately no one I know has a Haswell motherboard for some testing of the cpu.

This whole system often caused trouble, not wanting to boot and getting stuck in a loop before actually starting. Already swapped out everything else with spare parts I had (GPU, RAM, PSU) and this boot loop still occurs (3x power on/off), then theres the new temperature error on top.. I thought about just leaving the whole platform behind and upgrading to an i7 6700K with a new motherboard. The i7 4790K costs the same here, and since my motherboard might be a bit faulty as well, Id rather not take the risk keeping it.