i would do what fatburger suggested and download motherboard monitor and see what it says, but if you aren't having stability problems, i wouldn't worry that much.
<A HREF="http://mbm.livewiredev.com/download5.htm" target="_new">MB 5.1</A>
The best accelerator available for a Mac is one that causes it to go at 9.81 m/s2
My MB is ECS K7S5A, same cpu as yours, when I use volcano 6cu hsf, cpu reads 39 to 42 degree C at idle, but the fan is very noisy, I changed to Master Cooler DP5-xxx, it reads higher around 42 to 45, but quieter, (my case is opened two sides, 'cause I still upgrading). I still don't know which one to keep: lower temp with higher noise, or higher temp with lower noise. Which one do you like?
I have the same MB, with the stock hsf that came with my 1800+ my temps were running in the high 40's. I got a alpha hs, and the temps droped to 40c at idle. Then i got a case from coolerguys, and know my idle temps are 34c, and 37c at full load.