krscla,

Athlons are officially rated at 85 C max operating temp, some models are rated up to 90 C.

Pentium 4s are rated to similar levels if im not mistaken.

as for ideal motherboard-reported operating temperatures, below 40 C is good, hanggang mga 50 C okay pa yan. note that Athlon motherboards (particularly older ones) usually under-report cpu temperatures.