watercool and air cool

I just put a 80mm fan blowing to the CPU waterblock.
The cpu temp decrease by 8C at full load. What is going on?
Is it b/c I'm not reading the temp from the die but rather CPU back temp. Or I will have to do both air cool and watercool from now on to get better temp?

I VERY highly doubt that a fan blowing on your waterblock would actually cause an 8C decrease in temps unless you have almost no water moving through that block (in which case its acting like a large HSF combo. More likely air flow is reaching the thermistor on the motherboard and cooling it.

Josh

I would agree, if its AMD then your blowing air onto the thermasistor in the back to cool it.

Thunderbird users beware !!!!!

I thought so as well. Looking more closely at the Iwill KK266 motherboard and the thunderbird cpu and the thermister under the cpu socket. So I place a temp probe right on the cpu package to test my theory. My temp reading agree with the cpu reading from MBM. So here is my explanation

Since the thermister measure temp in the back of the cpu package. In a way it is measuring the temp of the ceramic cpu package. Ceramic conduct heat much better than organic package that are found in XP cpu. By using a fan blowing at the waterblock. The air flow goes between the waterblock and the ceramic package which cools down the package. Hence the big difference temp found between no fan and with fan.

The bottom line is anyone who read temp from the mobo can not be accurate at all. I would wonder how difference it is for organic package such as XP cpu.

Can anyone conduct this test for me if you have XP cpu. Just place a fan and blow in between the cpu and the heatsink to see if you have any difference in temp.