Accuracy of Motherboard Sensors

In general, how accurate are the temperature sensors that are built into a motherboard?

More specifically, does anybody know how accurate the sensors on an NF7-S are?

Thanks

Mike

I'd usually give or take 1-3 degrees. It depends on the sensor i guess.

Hmmm....

I ask since my temperatures are reported as 55C at load, which seems too high considering the specification of my computer:

AMD Athlon Mobile Barton 2400+ at 200x11 1.6V
Abit NF7-S
Thermaltake Volcano 12
Beantech Igloo 1 (including three fans)

try reseating the CPU with a thin layer of thermal paste

coming from a scientific background, a couple of degrees lateral is quite a lot, particularly when dealing with whats meant to be prescision kit!...

The NF7-S sensor is wild inaccurate at best, don’t trust it for a moment.

Quote:

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Originally Posted by Agent

The NF7-S sensor is wild inaccurate at best, don’t trust it for a moment.

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In that case, where is the cheapest place it would be possible to buy a thermal sensor?

You wont get measurements that are comparable between systems.

The best way if you want that, is to read the on-die diode, which amd placed there for this purpose.. but noone uses them :(
If you want to do this, you need to be able to solder very small chips (max6657 is an example), and wires to the back of you rmobos cpu socket, and you can only read it from pc software unless you create you program a PIC or something to read it..


Otherwise, its only relative to your system. Measurements can be +-15c, depending on the possible inaccuracys:

Sensor inaccuracy. Thermistors are commonly +-5°c variation between parts. They need calibrating - which is something done very wrong in mobo thermistor sensors.
Google for thermistor calibration.

Thermocouples are better, simpler and more accurate and more usefull/popular. They have much higher temp range, linear over full temp range unlike thermistors which only have a small range of linear use.
If you do this method, get yourself a multimeter, most have thermocouples included and work well. Thermocouples can be VERY small, as they consist only of two wires, twisted or wealded together. Where they meet, a voltage is created depending on the temperature. However many will be encased inplastic or metal to stop damage, but then wont fit under the cpu, so check :)

Mounting of sensor - TIM join thermal resistance to cpu/heat source (probably one of the biggest problems).This is removed in the on-die-diode sensors

ADC Conversion error, analoge signal interferance.. - pcb design is important, and using a good enough ADC chip..