Yeah, something isn't mounted right here. Pentium 3's simply don't run that hot, especially one with the CPU fan running at 3k RPM.
FWIW, I'm running the stock fan of my stock P3 heatsink on 7V, dropping the RPM from 5k to about 2.2k constant. And even with that, I have not seen my temperatures top 45-48C under load. It's a Pentium III 933 MHz Coppermine, for the record, and no head spreader.
If you are sure everything is mounted correctly (flip the fan too while at it, as others suggested), then perhaps the heat spreader on yours is starting to get poor coupling (due to dry paste) to the CPU core/die. In that case, you might have to delid the CPU and re-apply thermal paste between the die and heat spreader.
StriderTR wrote on 2025-03-02, 23:31:
However, the common recommendation is to change it out every 2-3 years or so, I check mine every 3 years unless I notice thermal issues sooner.
That's kind of a wasteful thing to do.
Just about any non-gabrage thermal paste can last for years or even decades, so long as it doesn't see very high temperatures (generally above 60C) and a high dissipation per small surface area (i.e. when you have a very small and hot silicon die trying to dissipate heat into a very large and cool heatsink.)
So for instance, I have an Athlon 64 X2 6000+ CPU on which I used the cheap no-name "gray" thermal compound stuff from Ebay and its stock (but relatively large) heatsink. Because I've always ran that CPU cool (under-clocked to 2.4 GHz most of the time and under-volted to 1.125-1.2V), the cheapo no-name thermal compound I used is still OK and hasn't dried or pumped out. FWIW, I put this machine back in 2014 - over 10 years ago now. It has seen moderate (though not everyday) use for retro gaming. And this is not my only example. I don't recall actually having to re-paste any of my systems. The CPUs with heat-spreaders are still showing the same load temperatures (or maybe increased by 1-2C tops) as the day I put them together (some with the same cheap no-name thermal compound, others with more proper stuff like MX2/4.)
So I think people underestimate how long thermal compound is supposed to last.
Now on new(er) PCs / CPUs / GPUs that run in the 60+ Celsius range, I can see that happening where the paste dries in 4-5 years or so, especially with heavy use. In fact, I have gotten many GPUs from Ebay with dry thermal compound that looks and performs completely like chalk. But that's because a lot of these cards ran at 70+ C with their stock coolers, and some were even clogged with dust, probably running close to 80C. With such high temperatures, thermal compounds DO start to dry. Repasting all of these and jacking up their fan profiles... or simply replacing their coolers with bigger ones... has not made them come back with dry paste yet.
Oh, and one last point: thermal compound is -reusable- , if still properly "moist".
With that said, I don't ever throw away old thermal compound anymore if it still appears to be normal. Instead I scoop it up and re-use it later on. To attest to this, I have several GPUs now running with -reused- thermal compound, some of which have been in service for a few years. Temperature-wise, they are within 2C to how they performed with new good brand-name thermal compound like MX4.
