Advice on sensor placement

[LifeIsTooShort]

I've followed the forums here for a while now (anonymously) but I just bought a new rig and as it has been a while since my last build (AMD Athon 800mhz were new!) I am looking for a bit of advice on the placement of a temperature sensor.

I bought an Antec P160 case (very sharp BTW, classy and not garish) which has a built in temperature readout. I would like to have one of the two sensors register the CPU heat as I plan on doing some mild OCing at some point. My question is, where do I place the sensor to accomplish this?

As an additional note, I also bought a couple of Thermaltake fans that have an automatic speed adjustment setting based on temp, and though I did not plan to use this feature I read in their instructions that the sensor, which is identical to the case's sensor, should be placed in between the CPU and the heatsink! Is this a good idea? I'm a bit leary about placing my case's sensor where it might obstruct the heat transfer to my HSF, but has anyone else done this successfully before? It does seem as though it would be the best place for an accurate reading...

Any advice is welcome and appreciated.

 

[MustISO]

You would place it on the underside of the heatsink but NOT in between the CPU and the heatsink.

 

[LifeIsTooShort]

Ok, thanks for the advice.

 

[flawlssdistortn]

I don't think there's enough room underneath with 939 pins!!