TechWhore
Air Temp, or Case temp... Even in optimal situations, a cpu will be at least 2C higher than the ambient case temperature at idle(since idle is not 100% idle, rather like 99.5% idle). In Order for you to be getting 18C idle temp, your air temp would
have to be around 50-60F.
Your cpu(@1ghz + 1.8V) puts out roughly 57w of heat, so at .4c/w with your heatsink, if you ambient was 16c, your full load temp would be at least 39C.(keep in mind, even with artic silver, this isn't achievable).
Note that your ambient idle cpu temp is not ambient air temp.
Zeroburn,
Your chip puts out roughly 30W, so getting a full load temp of 54 is a tad high. I'd check to make sure the heatsink is nice and flat on the cpu.
Mike