Let's see:
32 bit:
- generic PC Chips Celeron P3 tower
- HP Vectra VL400 (Pentium 3)
- generic Asrock Pentium 4 tower
- Packard Bell iGO 4000 (Pentium 4 M)
- iCOP 1st generation Vortex86
64 & 32:
- Thinkcentre M73 (whatever's after Ivy Bridge)
- Dell 755 (C2D, may get rid of it)
- Dell 7010 (Ivy Bridge, newest purchase and probably going to be my main desktop)
64 only (§):
- Huawei MateStation S (Ryzen 4600), funny enough this is by far the newest PC I have by manufacturing date and one I want to get rid of the most
Dubious:
- Vaio FZ21M (C2D, nv*dia'd)
-§ NEC TW708CAS (classic mid-2010s Win8 tablet, totaled eMMC)
- Chromebook Lick (Celeron-Atom N4000, designed for full 64 bit operation but I think it's plausible to compile a 32 bit EFI or even BIOS for it right now)
- generic Gigabyte micro ITX system (Celeron-Arrandale?, seems to have big firmware bugs and in my limited testing only works fine in BIOS emulation)
§ = 64 bit CPU but 32 bit EFI and/or no CSM (that conceptually sucks anyway)
Hmmm, almost a 50% split, I'd never have expected that!
(Of course, this is excluding all the things that never wanted, even only spiritually, to be "IBM compatible"...)