If I had to choose, I'd build a system around the XP 2800+. I'd say that's the best of the three. The PIII is probably better than the P4, despite the speed difference, if power is a primary concern, although I have yet to test the relevant platforms to know for sure. Just based on what I have read.

Via's KM- chipsets are basically identical to their more popular (with enthousiasts) KT-chipsets, just with added video, which is disabled if you use the AGP slot. So a board with KM266-Pro is for all intents and purposes the same as a similar board with KT266A chipset - a decent but not exceptional mid-SoA era chipset. As for the board - MSI board from that era were very decent, but invariably had bad caps that needed replacing. However if you're not sure of board ID, best to sort that out first.

A friend of mine rescued a huge pile of MS-6340 boards with bad caps back when SoA was still a viable mainstream option. Together with a friend he re-capped them and sold them for a small but handy profit. I don't recall exact numbers, but the vast majority worked after re-capping and he only had a handful of returns, most due to soldering errors. The rest went on to work for years more. MS-6340 was basically the old KM133 version of the MS-7061, so it has good pedigree.

Since the boards you're looking at already don't have ISA support, what about Socket 754 and an Athlon 64?

The later "Cool n' Quiet" CPUs are multiplier unlocked so you can underclock them, and they run cool. They are also compatible with modern AM4 coolers. I'm using the stock AMD cooler that came with a Ryzen 3700x in my A64 Win98 rig. And they work great with modern PSU, no high +5V requirement.

The board I'm using has a Via K8T800 that's been rock-solid, and it supports Soundblaster emulation in pure DOS with PCI cards.

MicroATX will limit your options, but I see MB, CPU, cooler, and 512MB combos for $50-60 shipped at the inflated eBay prices.

One thing to be aware of in the area of MSI mATX socket A boards with Via chipsets is that they did a few for OEMs like HP, and those versions are aggressively unsupported by MSI and have very limited BIOSes... though I don't know what stops you exactly from figuring out the closest retail model and using that BIOS. I have a board I meant to figure it out for, but I keep having nicer boards rise from the depths of the pile just as I think I'm about to use it, so haven't got to it.

An observation I have formed on limited data, so might be wrong, is that retail MSI boards are red while the OEM HP ones are green so "If it's red, go ahead", "If it's green, run and scream" might be a useful ditty ... or not.

I think part of the fun might be playing with what is essentially an integrated Savage 4. And you have an AGP slot so can go to something faster as well.

Hold up there, safety first, fasten your seatbelt before attempting 🤣

I caution against the HP ones, they don't allow much tuning, fast RAM is wasted on them, but support the basics, so if they're kicking around cheap enough, you could whack a Duron 800 in one and use that and the Via OGP (Which ones were unichrome??? Was that post KM333 and KM133 and KM266 were savage?) as a stand in for a 1999 PIII and TNT rig.

Edit: Sorting out that stray thought, KM400 up (They skipped KM333) used Unichrome, prior was ProSavage.... however Unichrome was only warmed over ProSavage with a dash of Tobasco... mmm vinegary.

dionb wrote on 2021-12-23, 20:25:

However if you're not sure of board ID, best to sort that out first.

The board has MS-7061 VER: 1.0 on it as an ID. Only I assumed it's a KM400 because when I searched it, I got some identical looking boards (only with SATA soldered on).

Details

The one I've mistaken for it:

The one actually listed:

Then after I opened the topic I noticed there is an image with the chipset heatsink off where it's visible that it's KM266-Pro instead of a KM400.

What caught my eye is MSI still having the 'DLC' for it.

SScorpio wrote on 2021-12-23, 20:39:

Since the boards you're looking at already don't have ISA support, what about Socket 754 and an Athlon 64? […]
Show full quote

Since the boards you're looking at already don't have ISA support, what about Socket 754 and an Athlon 64?

The later "Cool n' Quiet" CPUs are multiplier unlocked so you can underclock them, and they run cool. They are also compatible with modern AM4 coolers. I'm using the stock AMD cooler that came with a Ryzen 3700x in my A64 Win98 rig. And they work great with modern PSU, no high +5V requirement.

The board I'm using has a Via K8T800 that's been rock-solid, and it supports Soundblaster emulation in pure DOS with PCI cards.

MicroATX will limit your options, but I see MB, CPU, cooler, and 512MB combos for $50-60 shipped at the inflated eBay prices.

Socket 754 is very rare where I live. S462 is also getting rare so I'm really in a spot that if I want one for a good price I don't have much time to lose.
I'm planning a full ATX rig too, but it's for a different reason. For this one is specifically for an 'as compact as it can get' PC. DOS sound is not a preference for this one. I have a full ATX Pentium 2 rig for that. It'll run with the leftover SB0100 from the Tualatin build.

swaaye wrote on 2021-12-23, 20:43:

I think part of the fun might be playing with what is essentially an integrated Savage 4. And you have an AGP slot so can go to something faster as well.

I'm also curious about that, but I'll use a Ti4200, then later if I can fix my faulty FX-5700 then I'll probably upgrade. The FX crashes when it's driver installed.

RandomStranger wrote on 2021-12-23, 20:57:

[...] […]
Show full quote

[...]

The one I've mistaken for it:
000122_5.jpg

The one actually listed:
msi-ms7061-retro-socket-462.jpg[/details]
Then after I opened the topic I noticed there is an image with the chipset heatsink off where it's visible that it's KM266-Pro instead of a KM400.

What caught my eye is MSI still having the 'DLC' for it.

Odd, even by MSI standards. They've used different revisions of the same board for different chipsets (i.e. MS-6330 rev 1.0 K7TPro had KT133, MS-6330 rev 3.0 K7TTurbo had KT133A), but I've not seen quite different chipsets on same model number and revision before. But it checks out, if I look up MS-7061 KM266Pro I find the KM3M-V which appears to have exactly the same PCB, just different chipset and no SATA. That one's also still listed on MSI's site.

CPU compatibility looks OK for the 2800+:
https://www.msi.com/Motherboard/KM3MV/support … -main-block-qvl

FWIW, I recently used a new KM400 for my Windows 98 SE build (assuming the experience between the two boards should be in the ballpark of each other) and, it having been a number of years since I've built a machine for Win98, I found it relatively easy to get it running and stable since I was running off my knowledge base from my teens. I'm currently running a Radeon 9600, Athlon XP 1600+, and a stick of 512mb PNY PC3200 and overall it's been pretty stable with no BSoD. So far I've ran BG1, Doom (because of course), WC1, Duke Nukem 3D, and SiN without a problem. With the holidays here, I'm planning to dig into my library a bit and see about stress testing it a bit more - I can update if I find any issues. Sorry I can't give anything beyond a superficial analysis as I'm just getting (back?) into the retro PC scene so I'm having to get back up to speed.

One of them MSI (KM400AM) saved me a lot of time when I was looking for a board for a uATX case and a W98SE machine. The first intention to use Tualatin on i815/i810 failed on the impossibility of installing PCI audio with FM synthesis on ICH2 , eventually I ended up with MSI and Barton, where everything works without problems and even old DOS games run great.
Yes, BIOS tweak options are limited, The FSB is only set in steps 100/133/166 and 200 (depending on the chipset used) jumpers. The integrated S3G Unichrome (KM133 and 266 has a weaker ProSavage) will suffice for office use, don't expect miracles in 3D - some test: https://www.anandtech.com/show/686/11 https://www.svethardware.cz/recenze-fic-k7m-4 … d-palbou/9244-3
Southbridge 8237 means only SATA150 HDD, newer ones don't detect and not all of them go into SATA150 mode - with KM266 but SATA drops out entirely thanks to SB 8235.
In the others, the board is average, behaves steadily (even with original OST capacitors) and suits my needs (W98SE and its running DOS games).

SScorpio wrote on 2021-12-23, 20:39:

Since the boards you're looking at already don't have ISA support, what about Socket 754 and an Athlon 64?

The later "Cool n' Quiet" CPUs are multiplier unlocked so you can underclock them, and they run cool. They are also compatible with modern AM4 coolers. I'm using the stock AMD cooler that came with a Ryzen 3700x in my A64 Win98 rig. And they work great with modern PSU, no high +5V requirement.

Even though it doesn't seem so, Athlon XP is much more flexible compared to Athlon 64 - especially the Thoroughbred (many of which are unlocked). But even the Barton, when used on a good board, it can be extremely flexible (you can easily hit fast/slow 486 & fast/slow 386 speeds).
Then again, Athlon 64 on a VIA K8T800 board is also very good and it does have some nice advantages compared to the Athlon XP (like the fact that all boards work fine with modern PSUs).