No. It is a feature which is used for kernel mutex. It will refuse to boot.
However, there were guys that have had a battle for the slowest XP system:
https://www.winhistory.de/more/386/xpmini_en.htm

It seems like 18 MB or an 8 MHz clocked Pentium Overdrive without fan is the minimum.

Win 2000 will run on a 486, so maybe an early build of XP/Whistler will, as well ?

I've been researching this in the past, and from what I remember, the only times Windows XP checked for the CMPXCHG8B instruction are at the first part of the setup (i.e. after the "Setup is inspecting your computer's configuration" screen) and when attempting to do an upgrade install from an older Windows version.

The last (leaked) Whistler/Windows XP Beta build to not have the CMPXCHG8B instruction check was 2223. Build 2250 is the earliest build to implement the check.

As an experiment, I replaced the SETUPLDR.BIN file on a Windows XP Setup boot floppy image with the one from Whistler Build 2223. The CMPXCHG8B check was gone, but it showed a BSOD after the "Setup is starting Windows" screen (I can't remember the exact STOP error code, I want to say it was 0x7B (INACCESSIBLE_BOOT_DEVICE), but I could be wrong on that). I tested this on Virtual PC 2007 back then, so I don't know if it would do the same thing on a 486 (real or emulated).

If you have a 486 computer and a Pentium Overdrive CPU for it, you're welcome to try to install Windows XP with the Pentium Overdrive CPU installed then replace it with a 486 afterwards to see if it would still boot.

Lots of files have to be patched for doing so, but it is possible: https://msfn.org/board/topic/186080-xp-running-on-a-486-cpu/

KCompRoom2000 wrote on 2021-08-23, 06:05:

[...]

If you have a 486 computer and a Pentium Overdrive CPU for it, you're welcome to try to install Windows XP with the Pentium Overdrive CPU installed then replace it with a 486 afterwards to see if it would still boot.

I did that in the early 00's.

Installed WinXP on a late PCI-based 486 board with PODP83 and 256M RAM. Worked 'fine'. Replaced PODP with an Am5x86-133: no boot.

Then took heatsink off PODP (drops multiplier to 1x) and dropped FSB to 16MHz. "Worked", although it took a few hours to boot to deskop 😜

dionb wrote on 2024-04-15, 09:37:

I did that in the early 00's. […]
Show full quote

KCompRoom2000 wrote on 2021-08-23, 06:05:

[...]

If you have a 486 computer and a Pentium Overdrive CPU for it, you're welcome to try to install Windows XP with the Pentium Overdrive CPU installed then replace it with a 486 afterwards to see if it would still boot.

I did that in the early 00's.

Installed WinXP on a late PCI-based 486 board with PODP83 and 256M RAM. Worked 'fine'. Replaced PODP with an Am5x86-133: no boot.

Then took heatsink off PODP (drops multiplier to 1x) and dropped FSB to 16MHz. "Worked", although it took a few hours to boot to deskop 😜

Not booting after replacing PODP with an Am5x86-133, because NT kernel throws Stop error 0x0000005D early before switching to graphics mode.