I have a similar machine with two Deschutes 450 MHz Pentiums II and Windows 2000.

Just get another 350 MHz Pentium II and pair it with the one you already have. I *think* it doesn't have to be another SL2U3, but this tolerance probably varies from board to board. I don't know how yours will handle it.

Pentium II Xeon uses a completely different socket. You can't install them on that board. (There may be Slot 2-to-Slot 1 adaptors but I don't know anything about them.)

I also have a machine with quad 450 MHz Pentium II Xeons running Windows 2000 Server.

Quick google seems to suggest it uses BX chipset, best chipset for Slot1 IMHO.
My Duel Asus board says you need a CPU terminator if the 2nd slot isn't populated but plenty of people here are running fine without one so your probably safe as well.
You get the benefit of 4 Ram slots, most Slot 1 motherboards only came with 3, 1GB will be the limit most likely.

I did have mismatched PII 400's in mine long time ago, it would generate a error in the event log but run fine otherwise.

Best OS would be Duel boot Win2k/Win98
Most Win9x games run fine in Win2k
For the few that don't, Drop back to Win98
Plus you can use Win98 to drop back to dos, and you have isa slots for a dos sound card.

Here is mine if you want some inspiration 😉 It's my most PC when I just want to game.
Asus P2B-DS Build

I also have a similar spec Compaq Prolient 1600 running NT4 server which I use to backup all my retro games. But really its just an excuse for NT4 as its not much good at gaming.

dkarguth wrote:

I have no prior experience with Slot 1 boards or CPUs, so can anyone tell me if this motherboard and processor are decent? […]
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I have no prior experience with Slot 1 boards or CPUs, so can anyone tell me if this motherboard and processor are decent?

I found this motherboard for $7 at the local Goodwill brand new in box. I have had a Pentium II sitting on my shelf as a random decoration for 5+ years now, so I thought what the heck, I could build a Slot 1 machine. I noticed that it is a dual slot motherboard, will this cause any problems using it with only one processor? Also, if I wanted to use a Xeon in it, could I run a dual processor setup with a Xeon and a Pentium II? Like I said, I have no knowledge about Slot 1 boards, and I have never owned a dual processor board before. Is there anything crucial that I should know about Slot 1 motherboards before I start screwing around with it? I don't want to mess anything up or end up wasting hours on some silly common problem. I already spent an embarrassingly long time trying to remove the processor from the slot until I figured out it has latches...

Also, what would be the optimal OS to use with the machine? I thought about setting up NT4 or Windows 2000 to use it as a local webserver/file server just for kicks and giggles, but I'm not to sure how well it would run either of those.

Here's the motherboard:

Here is the Pentium II that I plan to use with it

I have a KP6-BS with dual Katmai CPUs. It's disgusting running Win NT 3.51 with 1 gb of RAM.

dkarguth wrote:

[...]

Also, what would be the optimal OS to use with the machine? I thought about setting up NT4 or Windows 2000 to use it as a local webserver/file server just for kicks and giggles, but I'm not to sure how well it would run either of those.

That's one sweet board 😀

NT4 and 2K will run fine on it if you provide enough RAM; 128MB or over and it will fly.

That said, unless you're a masochist, run your webserver on Linux, not Windows. Added advantage there is that you can actually run a completely modern, up-to-date OS that's safe to connect to the internet if you want. That said, don't expect to run the latest flashy composited desktop on a P2. Some Linux distros require SSE2 (min Pentium 4), but Debian/Devuan will run on any 686, which means Pentium Pro, Pentium II or later. Difference between Debian and Devuan is systemd. It's a topic that gets Linux folks quite heated, but for an older system the relevant bit is that systemd is a resource hog and you don't have resources to spare, so I'd recommend Devuan over Debian.

I'd suggest going for the text-based "Minimal install" and then manually installing the required packages (apache2 for HTTP, vsftp (or similar) for FTP, samba for Windows File & Printer Sharing). If you want a desktop, choose a lightweight thing like wmaker.

I second running a version of Linux in Console-mode only. I recently performed a Xeon LGA771-to-LGA775 mod on an old micro-ATX board. Put in 4GB of DDR2-800 memory and installed a Xeon E5450 and installed Ubuntu Server 18.10. Yes, it's complete overkill for a webserver or local file server, but I was planning to run PLEX media server and wanted to be able to transcode on the fly if necessary, so I went OP and maxed out the system. Two 350MHz P2s should be able to handle a simple at-home file server no sweat, though I don't think I'd recommend Ubuntu on anything less than 1GB of memory. My server usually hovers at ~760MB idle. Check out the Debian that dionb suggested. I'm pretty much new to the Linux scene and only used it to minimize resource requirements on the server, but it seems EXTREMELY stable, has low resource cost, and does its job well. The system also doesn't put out much heat, so it's very quiet with the installed Scythe Byakko 92mm CPU tower cooler (130mm tall).

And not that anyone cares, but I do have a 350MHz Pentium II sitting on my shelf, heatsink/fan combo and all. I'm not using it since I upgraded my system to a Pentium 3 a few years ago. Been taken apart and re-TIM'd with Arctic Silver 5.