W.x. wrote on 2021-03-06, 06:06:

So, what is latest SIS chipset, that supports Universal AGP (3.3v signaling), as far as I see, SIS 645dx is ok, but doesnt support 800 Mhz FSB and HT, and Prescott CPUs.
651 seems same as 645dx, only better integrated graphics? Also built in support for USB 2.0. What about 648fx? This supports HT for sure, 800 Mhz p4 too, but not sure if there are some boards, that supports Universtal AGP 2x,4x, so 3.3 v signaling. Because Asus P4S800 doesnt support it, only 1.5v AGP cards. Not sure, if this apply to all 648fx motherboards.
Anyway, what's last SIS chipset for P4, that can support AGP 2x 3.3v cards?

Iv got a 645 chipset that only takes 533fsb Northwood CPU's and doesnt support HT with a universal AGP Pro slot. It actually takes the 3.06ghz Northwood just without HT. So the 645dx will actually work with the same chip and HT enabled. EDIT: Apparently it's only the B stepping of the 645dx chipset that allows HT and you also need a bios with HT support after reading a couple old Overclocker's forum threads.

Talking about SiS chipset under Windows98/95 and <2000 year My experience with SiS chipset is as good as Intel / Via chipsets, never had any particular problem. And i also think that SiS chipsets from series 5xx onwards are underrated. Especially the SiS 630T / ET. Motherboards under my hands had optimized very quick boot times ( faster than more famous brands ), performance similar to other chipsets and perfectly reliable under Windows 98 and games. Latest motherboard with SiS chipset was the Asus CUSI-FX and ran perfectly fine, under stress, no driver problems......etc

Whoa, necropost. While on the topic, Scrap Computing revisited the SIS 540 chipset last year and had some interesting results tweaking the FSB with PC133 SDRAM.

https://youtu.be/_hemUMLIhWw

It's a shame the majority of boards with this chipset are PCChips.

Socket 7 mobos ranged from crap to mediocre

Mobos for slotted CPUs and newer tended to be pretty good and required less "gymnastic" with AGP drivers than contemporary VIA mobos.

Albeit nobody cared at the time, they run fresher than other chipsets from Intel/VIA and others.

The SIS 85C406/411/431 is the only universal baby-AT EISA motherboard for socket 3 (486). Very fast when I tested it.