ABIT AN8 Ultra :
 

The AN8 Ultra is ABIT’s newest Athlon64 that uses heat pipe technology to cool its nForce4 Ultra chipset. Read on to find out if this new feature has any effect on the board’s performance…

http://hardocp.com/article.html?art=ODAx

So much for heatpipe passive cooling ..... nothing is perfect. Like burning candle in both ends, there must be min. temperature differentiations or it won't work.