3dfx_fan wrote on 2025-09-23, 10:08:

I have similar problem to this:
Pentium 3 500 won't hit 500mhz?!
But in my case Pentium III 500Mhz does not work with Asus P3B-F completely at all at any FSB speed (does not matter if using junpers or jumperfree), while this CPU (Pentium III 500Mhz) works on another motherboard. My P3B-F seems to start fine with Pentium II 333MHz and Pentium III 450Mhz, but not with Pentium III 500Mhz. This motherboard has also broken PS/2 mouse port and PS/2 mouse don't work ("!" in yellow triangle id device manager) and I use USB mouse, but that should have nothing to do with CPU problems.

I suppose the motherboard works with another CPU, I have a similar problem with a motherboard, in my case a Soyo BX, it works with the Celeron FSB 66, and also with the Celeron overclock to FSB 100, it also works with a PII 300/66, any CPU FSB 100 or 133 does not work, even using Slot1 370 adapters, it could probably be a problem of contacts of the Slot1, or other, maybe try to clean the contacts of the CPU PIII 500, or spray a deoxidist, even a cleaning of the Slot1 (contacts), could improve the contact between CPU and Slot 1, if you're lucky 🍀, it could work.

3dfx_fan wrote on 2025-09-23, 10:08:

I have similar problem to this:
Pentium 3 500 won't hit 500mhz?!
But in my case Pentium III 500Mhz does not work with Asus P3B-F completely at all at any FSB speed (does not matter if using junpers or jumperfree), while this CPU (Pentium III 500Mhz) works on another motherboard. My P3B-F seems to start fine with Pentium II 333MHz and Pentium III 450Mhz, but not with Pentium III 500Mhz. This motherboard has also broken PS/2 mouse port and PS/2 mouse don't work ("!" in yellow triangle id device manager) and I use USB mouse, but that should have nothing to do with CPU problems.

https://theretroweb.com/motherboards/s/asus-p3b-f#chips
https://theretroweb.com/chip/documentation/as … 81946939863.pdf

Pins 81 and 84: measure when cpu is PIII-500 and other working cpus. See if there ia a vcore consistent ok value for the working cpus.
Pins 72-76: VID0-4

Could be detecting incorrectly and one of these is abnormally low or high...

Wild guess.

Tried with another Asus P3B-F and effect was the same - Pentium III 500 Mhz did not boot/POST.
Pentium II 333 MHz - starts/POST.
Pentium II 350 Mhz - starts/POST.
Pentium II 400 Mhz - starts/POST.
I don't own Pentium II 450 Mhz.
Pentium III 450 Mhz - starts/POST.
Pentium III 500 Mhz - does not start/POST (but it starts/POST on another motherboard).

3dfx_fan wrote on 2025-10-31, 09:51:

Tried with another Asus P3B-F and effect was the same - Pentium III 500 Mhz did not boot/POST. Pentium II 333 MHz - starts/POST. […]
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Tried with another Asus P3B-F and effect was the same - Pentium III 500 Mhz did not boot/POST.
Pentium II 333 MHz - starts/POST.
Pentium II 350 Mhz - starts/POST.
Pentium II 400 Mhz - starts/POST.
I don't own Pentium II 450 Mhz.
Pentium III 450 Mhz - starts/POST.
Pentium III 500 Mhz - does not start/POST (but it starts/POST on another motherboard).

Strange behavior but interesting 🧐
But maybe it's just some oxidized contact of the Slot1, it could be that some pins of the Slot1 do not make contact, and therefore for example does not match the multi, and the result is the failure to start.
Undoubtedly if the CPU works, it is a problem of the Slot1, but I would say that maybe the CPU should also be checked, and a revived to the contacts, would be done, do not use anything abrasive however, if even after cleaning it does not work, it would be to try with a Slot1 370 adapter or a Celeron 333 Slot1, at FSB 100 it would go to 500 MHz, this shows (if it works) that the problem is with that CPU, I on the Soyo for the moment I solved it like this, but it would be better to find someone who has several CPUs P3 500 Slot1, if it does not work with the others, I would try with a 550 or a 600, if they work, the suspicion on the Slot1 pins could be well-founded.