Core equal to ambiant?

squiffy · 24 Aug 2006 at 11:29

Set to 2.2ghz stock (4400+ X2) with CAQ enabled, in portable/laptop mode (1.1ghz) core 0 is at 19/20, core 1 23/24. Ambiant is 20.

Is it possible to have CPU cooler than room temp? If the airflow is so great isn't there a "wind chill" factor for heasinks? :confused:

A.N.Other · 24 Aug 2006 at 11:33

AFAIK no. Both air and water can't cool below ambient.

Sounds like a faulty reading to me.

feriso · 24 Aug 2006 at 12:34

Sorry to but in but how do you find the temps of each core? - got a 3800x2 on a abit kn8 and can't seem to make sense of the temps from speedfan

fornowagain · 24 Aug 2006 at 13:08

squiffy said:
Is it possible to have CPU cooler than room temp? If the airflow is so great isn't there a "wind chill" factor for heasinks?

Um, no. Thermodynamically impossible, but nice try.

cpu dT = (cpu load T) - (room ambient T)
Thermal Resistance (TR) = (cpu dT) / (cpu watts)

An average HSF may have a TR=0.17C/W. Say for idle, a wattage could be as low as just 30W. That's gives a 5C delta. So for an ambient of 20C, that's more like 25C for the cpu. In the real world that would be higher because of losses. It could just be a sensor offset.

welshtom · 24 Aug 2006 at 13:17

The wind chill factor applies to us humans because as the wind blows it evaorates the moisture in our skin, thus evaporation takes the temperature down.

with a metal heatsink, no windchill occurs for fairly obvious reasons i would say

w3bbo · 24 Aug 2006 at 13:24

So in theory..spitting on a heatsink therby creating moisture that could be evaporated could cause 'windchill' and lower temps?

...I'll get my coat

welshtom · 24 Aug 2006 at 13:42

w3bbo said:
So in theory..spitting on a heatsink therby creating moisture that could be evaporated could cause 'windchill' and lower temps?

...I'll get my coat

In theory and in practice.

its bascially how phase change works (mach 2, vapochill)

high pressure liquid is forced to the evap head, where it evaporates taking the heat away, then condenses again to a liquid and the cycle continues.

Tom

fornowagain · 24 Aug 2006 at 13:46

Ever seen a cooling tower? Evaporative cooling is very efficient in the right climate (high temp, low RH). Surface molecules leave the liquid, the ones left behind have a lower "average" kinetic energy, so the temperature of the liquid decreases. It called the latent heat of evaporation during phase change.

You could make a very efficient cooling system with a normal water cooling rig and diy cooling tower. Far better than blowing air over a radiator. But the tower would have to be outside, so not very practical.