As I type this, my CPU temp is 66F(19C), the ambient room temp. at this moment is 68F(20C). Here is a screen capture: (note: this is with ACPI disabled in W2K - keep in mind, if ACPI were enabled, temps. would be significantly lower due to the built-in software CPU cooling.)
Under full load, my CPU temps. range any where in between 75-80F(24C-27C). I have never seen the CPU temp. over 80F(27C).
The VCore is actually set to 1.80V in the BIOS. The proc. that was in this computer before was a 1Ghz T-Bird OC'd to 1.2Ghz @ 1.8V. The idle temperature for that processor was 38-40F. As you can see, this Thunderbird gets EXTREMELY hot, I estimate the processor at this speed and voltage is radiating approximately 91W of heat!. That is nearly twice the amount of the 1Ghz T-Bird. Palomino, where are you? I am approaching, more likely exceeding the limit of the effectiveness of the 156W TEC. A 180W TEC and/or a water chiller is next on the agenda for this computer. SwiftTech claims that the MCW-462 is able to dissipate up to 300W of heat.
As you can see, this is some pretty impressive cooling. I'm not saying this is as impressive as Vapochill or nitrogen-cooled systems, but this is as close as one can get, I believe, to this while trying to cool a Thunderbird at 1.6Ghz.
I do not believe I have hit the limit of this core yet. I am only using 1.8V (1.85 actual). I still have plenty of voltage headroom to play around with. Once I get the cooling a bit lower with a stronger TEC and/or a chiller, a voltage modification to the motherboard will be in order. I have seen this processor stepping over-clock to +2.0Ghz, with a VMOD and extremely hard-core cooling.
If you're interested in any of the hardware/materials I used, I've put together a Links page. For a similar article on how to build a cheap, reliable water-cooling set up, here is an excellent article from HardwareOC.