bloodem wrote on 2022-12-05, 17:02:

Yeah, stay away from 2.9V, because it will cause a chain reaction that would unravel the very fabric of the space-time continuum […]
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gaffa2002 wrote on 2022-12-05, 16:43:

Quick update, switched back to 3x66 as the computer was restarting randomly at 100x2. Maybe changing voltage to 2.9 could solve the issue but I rather not mess with it.
Well, never had any luck overclocking CPUs or GPUs anyway...

Yeah, stay away from 2.9V, because it will cause a chain reaction that would unravel the very fabric of the space-time continuum and destroy the entire universe! 😁

Seriously, though, I've ran these chips at 3.1V / 292 MHz for EXTENSIVE periods of time (1 - 2 months / 3 - 4 hours a day). As long as you have adequate cooling (a bigger socket 370 cooler would be perfect), then you have absolutely nothing to worry about at 3.1V.
And as for 2.9V... yeah... any socket 7 heatsink will do and there is absolutely NO risk of damaging your CPU.

In other news... am I missing something? 😀 These CPUs are not rare, you can usually get a Pentium MMX for ~ $10 - $15 (sometimes for less/free). So even if you were to destroy one, it's not the end of the world. 😀

TBH is not about money, is more about not caring enough to risk breaking and replacing the CPU. I'm much more of a software person and not a fan of opening cases, installing cards or setting up switches. My "retro fun" mostly comes from playing games and creating programs and scripts.

For the P55C:

wikipedia wrote:

It contained 4.5 million transistors and had an area of 140 mm2. It was fabricated in a 0.28 μm CMOS process with the same metal pitches as the previous 0.35 μm BiCMOS process, so Intel described it as "0.35 μm" because of its similar transistor density.

Because it has the same metal pitches as the previous gen designed for 3.3V, maybe it's fine. It seems they changed the process to support a larger number of transistor on die with the addition of MMX. Dropping the voltage seemed to keep the TDP the same as the previous gen. So it seems their concern was to not blow a power or cooling budget for the systems these chips were going in at the time. Assuming power is not a concern, I don't know what the maximum speed would be for these chips. If they fail to work at an overclock, then there is some kind of chip or board timing issue.

If you can increase the multiplier without increasing voltage, and if you can cool it adequately then I would say no.