# Best way to connect temp. sensors to CPU / GPU



## Derek895 (Feb 17, 2005)

I have just got a new case which has a temperature readout for HDD/CPU/GPU. I haven't installed the CPU yet and so haven't attached the fan. I was wondering should the sensor be placed directly onto the CPU or on the heatsink? Also the sensor for the graphics card - do I need to remove the heatsink/fan to apply it?

Thanks,

Derek


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## UncleMacro (Jan 26, 2005)

Assuming you have a Pentium 4 CPU, it's better to just read the temperature with the internal diode built into the chip. It will be more accurate. You could just stick the CPU sensor to a hard disk or something else. On most video cards, you can stick the sensor to the back of the video card at the center of the spot where the GPU is soldered to the other side of the circuit board. You can tell where that is by looking carefully at the circuit board traces. They all converge on a single spot. Just keep in mind that the temperature read out by those stick-on sensors will vary quite a bit depending on where you hook them. You try to get them as close as you can to the heat source but being sure not to get any part of them between where the chip package and the heatsink contact each other.


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## feddup (Oct 16, 2004)

*wondering!*

I've wondered about this myself. I've seen several manufacturers of fan controller/moniter hardware that suggested putting the sensor between the CPU and heatsink. With contact being so critical between those items this sounds like a really bad idea. Part of the reason this interests me so much is that I've had such poor experiences with monitoring software (MBM, Asusprobe, coolmon, speedfan etc.) that I'm looking for a hardware solution that I can monitor from the front of the PC. There are tons of them but it seems that sensor location would be critical. I want a redundant way to check the software tools. Anyway where are others putting the sensors for the CPU for greatest accuracy.


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## UncleMacro (Jan 26, 2005)

> several manufacturers of fan controller/moniter hardware that suggested putting the sensor between the CPU and heatsink


That's certifiably insane! Although it probably will give a fairly accurate reading of the substantially higher than normal temperature you get when the heatsink is not seated properly.

The P4 internal diode has a good reputation and I don't think there's any way for software to screw it up. I have speedfan set up to display my CPU temperature in the taskbar tray for my P4C800-E and it always returns a reasonable value. I think it's other CPUs which use a heat sensor underneath the CPU socket which tend not to be all that accurate. But you're unlikely to get a matching temperature from an external sensor because the P4 diode measures the temp on one specific part of the die and an external sensor is, well, external. They'll move together but don't expect them to match.

If the bottom of your heatsink is copper then you could stick the sensor to the bottom of the heatsink just outside of the area where the P4 heat spreader contacts the heatsink for a good reading. You'd better get the position just right or the heatsink won't seat properly.


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