This was what's in the manual btw:

Supposedly supported up to 1.26GHz even, unknown if they're referring to the S or non-S version. But maybe the 1.4GHz version wasn't released yet? The manual is dated 2001 and the 1.4GHz versions came out later than the first wave of Tualatin's (Q4 2001/2002 vs. July 2001) so that would seem logical.

PleaseHelpMeAdmin wrote on 2023-12-05, 08:25:

support Tualatin CPU

CT-6VIA5T and CA64-TC both support 1.4GHz Tualatin, make sure to update BIOS.
For the DFI board, difference between B and C revisions is audio codec used.
CPU-upgrade info is often unreliable and incomplete.

Bruno128 wrote on 2024-01-06, 11:05:

[...]

CPU-upgrade info is often unreliable and incomplete.

Yep. It's based on what is in the manuals of a board, so is limited to what was available at time of writing thereof.

In general, if any CPUs from a particular family with a particular stepping are supported, they all will be. The only concern is whether the higher-clocked ones draw more power than the VRMs on a motherboard can handle, but that's generally only an issue with notoriously hot CPUs, which the Tualatins are not.

If you want official info from manufacturer rather than educated guesswork, find the release notes for later BIOS revisions. They will generally say which CPUs are explicitly supported by that BIOS on that board. Of course, this means you need to be able to find said release notes and the vendor deigned to put that info in it. No idea how likely that is for Chaintech and DFI board from around the turn of the millennium.

So I've gotten a CA64-TC and now a QDI Advance 10T. Both do NOT take the Pentium III-S. Note that I'm referring to the version of the Tualatin with the additional IHS:

https://www.cpu-world.com/CPUs/Pentium- ... 0512).html

It will simply not fall in the slot. There are no pins bent. Could it really be that the lay-out of the non-S P3's deviates from the P3-S?

Mechanically there is no difference between PPGA, FC-PGA and FC-PGA2. If your CPU doesn't fit physically into any So370 socket, there's something wrong with either pins or socket.

If you're seeing the same on two boards, I'd focus on the CPU. No pins are totally bent but looking at the pic it looks like at least the bottom row of pins isn't perfectly aligned (left side slightly more 'up', right side slightly more 'down').