Pentium III Heat Issues

The first thing to take note is that, as mentioned in the Pentium III First Look, the processor doesn't come with a fan, and it runs HOT. With a heatsink alone, in an open-air environment, we measured the temperature of the heatsink directly over the contact point with the CPU package, at a blistering 79.3 degrees Celsius. I took a Socket-370 fan and jury-rigged it to the P3 heatsink, and saw the temperature drop to 39.1 degrees. The following charts gives you an general idea of what to expect, both open and closed-case, from the Pentium III. The Pentium II 500 is a P2-450 overclocked 4.5 x 112Mhz, and the Pentium III 416 is the P3 500 underclocked to 500 x 83.3.

P3 Operating Temperature - Open Case Ambient Temp 19.2°C
CPU speed	Without Fan:	With Fan:
Pentium 3 - 500	79.3°C	39.1°C
Pentium 3 - 416	66.1°C	37.3°C
Pentium 2 - 500	48.2°C	32.7°C
Pentium 2 - 400	42.8°	32.1°C

Well Ventilated Closed Case Internal Temp 26.2°C
CPU speed	Without Fan:	With Fan:
Pentium 3 - 500	84.6°C	45.3°C
Pentium 3 - 416	74.5°C	42.4°C
Pentium 2 - 500	53.1°C	37.5°C
Pentium 2 - 400	49.6°	36.7°C

The moral of the story? This isn't a Celeron Processor - if you're getting a Pentium III, get it with a heatsink/fan combo. We don't know why Intel would ship out CPUs without fans, especially considering the fact that like the Pentium II, the factory-installed heatsink requires 40 lbs. of pressure to remove (but at least the P2 had a decent fan).

Now that we've got adequate cooling, what kind of performance can we expect by overclocking the CPU? The P3 is based on the same .25um manufacturing process as the P2, so we were curious to test the tolerances of the process.