Ozzuneoj wrote on 2026-08-21, 03:53:

Yeah, I have been collecting for many years and it wasn't until 2023 that I stumbled across my first K6-III (had also never had a 2+ or a III+). They are pretty uncommon unless you're diligently looking and willing to spend some money.

I have found tons of K6-2 500s though. Seems like they made an awful lot of that particular model. And they are great processors for retro PCs, for sure. I have had one in a dedicated DOS\98SE system for close to 20 years. I only ever used it for games made before 1999 and it worked great for that.

Yes, it's uncommon to see a K6-III on an old PC, but there used to be tons of cheap embedded K6-IIIs on eBay, so there was no reason to run a K6-2 in a retro PC. But apparently that is not the case anymore.

Ozzuneoj wrote on 2026-08-21, 03:53:

To be honest, getting a Windows XP system to run everything from 1999 and up is a great next step up from a K6-2 system. The cut-off for the year would depend mostly on whatever GPU you can get your hands on, though running the oldest games may get a little more complicated if you go with a newer card. To save costs you could get a PCI-E based system. You can get some dirt cheap but really nice GPUs that will run the vast majority of games back to 1999 with absolutely no concerns about performance or graphics settings.

I think what a lot of people do these days is just grab some old outdated Optiplex from the Core 2 through 3rd Gen i5 era, throw in some old card from 2009-2014 that has XP drivers and you've got a system that will fly for games of that time period.

Getting a Windows XP retro PC may be cheap, but having the space to keep multiple retro PCs *and* a modern PC as well is not. Sure, if you happen to have the empty space you don't need for anything else, then there's no reason to not have multiple builds, but that's not the case for everybody.

Mike_ wrote on 2026-08-21, 05:32:

Getting a Windows XP retro PC may be cheap, but having the space to keep multiple retro PCs *and* a modern PC as well is not. Sure, if you happen to have the empty space you don't need for anything else, then there's no reason to not have multiple builds, but that's not the case for everybody.

One good solution for those with limited space is using an SFF system and hooking it up to another input (or a switch box) on a monitor you're already using. Even Micro\Tiny sized systems from the early 2010s are very fast for games from the early 2000s. I think an HD4000 (Ivy Bridge integrated graphics) easily scores over 20,000 in 3dmark2001SE. You can get a Lenovo M92P Tiny, all ready to use for under $100 US, and you'll have a very capable XP-compatible system that's about the size of a Wii.

Of course, that feels a little like cheating if you enjoy building and working with a full size desktop from the time period. Still, it is an option for those that may need it. 🙂

Lylat1an wrote on 2026-08-21, 05:27:

Thank you for your replies, everyone. […]
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Thank you for your replies, everyone.

I have a GeForce 2 MX on order for now.

Would it be possible to upgrade the motherboard to safely handle a more power-hungry GPU in the AGP slot, and possibly other motherboard power components for more demanding games?

I'm using a modern 600w ATX PSU.

Sorry, I missed this post earlier.

The Geforce 2MX is a good choice! You will gain very very little from upgrading the video card past that with a K6-2 processor. If there are any AGP power mods that exist for this particular PC-Partner board, it wouldn't really be worth it.

Just going by this chart, a Geforce 2MX will likely give you 80-90% of the frame rate that your CPU is capable of pushing in most games from 1999 and earlier. With that last 20% only equating to maybe 5-10fps difference at most, it won't really change which games you can or cannot play. The processor won't be able to handle most 3D games newer than that, so there isn't much to be gained from upgrading the video card.

Lylat1an wrote on 2026-08-21, 05:27:

I'm using a modern 600w ATX PSU.

Any sense buying modern PSU for old hardware?

Ozzuneoj wrote on 2026-08-21, 06:22:

The Geforce 2MX is a good choice! You will gain very very little from upgrading the video card past that with a K6-2 processor. If there are any AGP power mods that exist for this particular PC-Partner board, it wouldn't really be worth it.

Just going by this chart, a Geforce 2MX will likely give you 80-90% of the frame rate that your CPU is capable of pushing in most games from 1999 and earlier. With that last 20% only equating to maybe 5-10fps difference at most, it won't really change which games you can or cannot play. The processor won't be able to handle most 3D games newer than that, so there isn't much to be gained from upgrading the video card.

I could get a 550MHz K6-III+, but I don't feel like spending $350 on one at the moment. :P

shevalier wrote on 2026-08-21, 08:10:

Lylat1an wrote on 2026-08-21, 05:27:

I'm using a modern 600w ATX PSU.

Any sense buying modern PSU for old hardware?

https://seasonic.com/core-gx/#specifications

I have the 650w version, actually.

20 watts for the 3.3 and 5 volt outputs, 100w combined.

I'm guessing that isn't bad considering it's "modern".

Too bad reliable AT PSUs don't seem to be made anymore.

Lylat1an wrote on 2026-08-21, 10:40:

I could get a 550MHz K6-III+, but I don't feel like spending $350 on one at the moment. 😜

And you really shouldn't, to be honest. 😁 For starters, getting an industrial Pentium 4 motherboard with an ISA slot would cost less than half of that, and a Socket A motherboard with ISA slot for an Athlon XP would be even less. Both of these options would be far more powerful than a K6-III, and CPUs for them are cheap.

Also, 400MHz K6-III+s that were meant for embedded systems have stock voltage of just 1.6V. They should almost always overclock to 500MHz if run at 2.0V, which is often the lowest voltage setting many super socket 7 boards have. If the board doesn't go lower than 2.2V, then you shouldn't use K6-III+.

Ozzuneoj wrote on 2026-08-21, 05:47:

One good solution for those with limited space is using an SFF system and hooking it up to another input (or a switch box) on a monitor you're already using. Even Micro\Tiny sized systems from the early 2010s are very fast for games from the early 2000s. I think an HD4000 (Ivy Bridge integrated graphics) easily scores over 20,000 in 3dmark2001SE. You can get a Lenovo M92P Tiny, all ready to use for under $100 US, and you'll have a very capable XP-compatible system that's about the size of a Wii.

Of course, that feels a little like cheating if you enjoy building and working with a full size desktop from the time period. Still, it is an option for those that may need it. 🙂

I guess that will also work. Or you can get a more powerful retro PC if you want an all-in-one solution.

Mike_ wrote on 2026-08-21, 15:52:

And you really shouldn't, to be honest. :D For starters, getting an industrial Pentium 4 motherboard with an ISA slot would cost […]
Show full quote

Lylat1an wrote on 2026-08-21, 10:40:

I could get a 550MHz K6-III+, but I don't feel like spending $350 on one at the moment. 😜

And you really shouldn't, to be honest. 😁 For starters, getting an industrial Pentium 4 motherboard with an ISA slot would cost less than half of that, and a Socket A motherboard with ISA slot for an Athlon XP would be even less. Both of these options would be far more powerful than a K6-III, and CPUs for them are cheap.

Also, 400MHz K6-III+s that were meant for embedded systems have stock voltage of just 1.6V. They should almost always overclock to 500MHz if run at 2.0V, which is often the lowest voltage setting many super socket 7 boards have. If the board doesn't go lower than 2.2V, then you shouldn't use K6-III+.

Ozzuneoj wrote on 2026-08-21, 05:47:

One good solution for those with limited space is using an SFF system and hooking it up to another input (or a switch box) on a monitor you're already using. Even Micro\Tiny sized systems from the early 2010s are very fast for games from the early 2000s. I think an HD4000 (Ivy Bridge integrated graphics) easily scores over 20,000 in 3dmark2001SE. You can get a Lenovo M92P Tiny, all ready to use for under $100 US, and you'll have a very capable XP-compatible system that's about the size of a Wii.

Of course, that feels a little like cheating if you enjoy building and working with a full size desktop from the time period. Still, it is an option for those that may need it. 🙂

I guess that will also work. Or you can get a more powerful retro PC if you want an all-in-one solution.

In my case, I just like the old IBM PC XT cases and wanted to upgrade one to the limit.

I've seen some industrial AT boards, but I don't think they'll fit under the drive bay.

Lylat1an wrote on 2026-08-21, 10:40:

Ozzuneoj wrote on 2026-08-21, 06:22:

The Geforce 2MX is a good choice! You will gain very very little from upgrading the video card past that with a K6-2 processor. If there are any AGP power mods that exist for this particular PC-Partner board, it wouldn't really be worth it.

Just going by this chart, a Geforce 2MX will likely give you 80-90% of the frame rate that your CPU is capable of pushing in most games from 1999 and earlier. With that last 20% only equating to maybe 5-10fps difference at most, it won't really change which games you can or cannot play. The processor won't be able to handle most 3D games newer than that, so there isn't much to be gained from upgrading the video card.

I could get a 550MHz K6-III+, but I don't feel like spending $350 on one at the moment. 😜

Absolutely... there is no point in doing that for such a small performance bump. Just spitballing, but that $350 unicorn of a CPU is only ~30% faster than what you have in the best case scenario.

This is just the limit of Socket 7.

Ozzuneoj wrote on 2026-08-22, 03:08:

Just spitballing, but that $350 unicorn of a CPU is only ~30% faster than what you have in the best case scenario.

This is just the limit of Socket 7.

And this motherboard seems to be the limit of what will fit in an IBM 5160 case with ISA and AGP slots.

All the newer ones look longer, and have components that won't slide beneath the low-hanging drive bay.

Would there be any point in trying a 3D accelerator card? I have an available PCI slot.

Perhaps some day I will get that K3, and a faster GPU that runs off a 4-pin power connector.

Ozzuneoj wrote on 2026-08-22, 03:08:

Lylat1an wrote on 2026-08-21, 10:40:

Ozzuneoj wrote on 2026-08-21, 06:22:

The Geforce 2MX is a good choice! You will gain very very little from upgrading the video card past that with a K6-2 processor. If there are any AGP power mods that exist for this particular PC-Partner board, it wouldn't really be worth it.

Just going by this chart, a Geforce 2MX will likely give you 80-90% of the frame rate that your CPU is capable of pushing in most games from 1999 and earlier. With that last 20% only equating to maybe 5-10fps difference at most, it won't really change which games you can or cannot play. The processor won't be able to handle most 3D games newer than that, so there isn't much to be gained from upgrading the video card.

I could get a 550MHz K6-III+, but I don't feel like spending $350 on one at the moment. 😜

Absolutely... there is no point in doing that for such a small performance bump. Just spitballing, but that $350 unicorn of a CPU is only ~30% faster than what you have in the best case scenario.

This is just the limit of Socket 7.

Some 440ZX motherboard, like the ASUS P2-99B with a Celeron 300A (overclocked to a 100 MHz FSB = 450 MHz), would be way more interesting in terms of performance.
https://theretroweb.com/motherboards?page=1&i … tIds%5B0%5D=287

But let's be honest, the popularity of the K6-2/3 was born from the rather nutty idea of getting an all-in-one PC that could run everything "from DOS to Windows XP".

Lylat1an wrote on 2026-08-22, 03:50:

And this motherboard seems to be the limit of what will fit in an IBM 5160 case with ISA and AGP slots. […]
Show full quote

Ozzuneoj wrote on 2026-08-22, 03:08:

Just spitballing, but that $350 unicorn of a CPU is only ~30% faster than what you have in the best case scenario.

This is just the limit of Socket 7.

And this motherboard seems to be the limit of what will fit in an IBM 5160 case with ISA and AGP slots.

All the newer ones look longer, and have components that won't slide beneath the low-hanging drive bay.

Would there be any point in trying a 3D accelerator card? I have an available PCI slot.

Perhaps some day I will get that K3, and a faster GPU that runs off a 4-pin power connector.

Yeah, if you've done the measurements and checked for clearances, then you've probably found the limit of the case. Going from the mid eighties to the late 90s is pretty good though, I'd say. 😀

The Geforce2 MX you bought is a 2D and 3D accelerator. Do you mean a dedicated 3D-only card like a Voodoo 1\2 or PowerVR PCX2? The Geforce2 MX will completely blow away any of the 3D-only accelerator cards from the 90s. If you want to tinker with them just as part of the experience, then yeah, a Voodoo2 is a nice match for a K6-2. Just know that it is about 1/4 the speed of your Geforce2 MX in most games, and it'll be quite a bit more expensive. In some situations performance may not be much different due to the K6-2 bottlenecking the Geforce2 MX already.

A K6-III won't really open up too many new capabilities for the system... just a moderate performance improvement in whatever already works on it. If you find one for a reasonable amount of money though, there is absolutely nothing wrong with maxing out a 5160 chassis by upgrading to a K6-III+ or something like that. 😁

And I really don't think there is any point in trying to use a GPU that runs off the 4-pin power connector in this system. As mentioned before, there isn't much performance left for a Socket 7 system to make use of, even with a K6-III+. And it is likely that any card that needs an auxiliary power input will pull more from the AGP slot than a lower end card anyway, and won't actually be much of an improvement over a Geforce2 MX, Geforce4 MX or Radeon 92xx... again, because of the CPU limitation.

shevalier wrote on 2026-08-22, 04:05:

Some 440ZX motherboard, like the ASUS P2-99B with a Celeron 300A (overclocked to a 100 MHz FSB = 450 MHz), would be way more int […]
Show full quote

Ozzuneoj wrote on 2026-08-22, 03:08:

Lylat1an wrote on 2026-08-21, 10:40:

I could get a 550MHz K6-III+, but I don't feel like spending $350 on one at the moment. 😜

Absolutely... there is no point in doing that for such a small performance bump. Just spitballing, but that $350 unicorn of a CPU is only ~30% faster than what you have in the best case scenario.

This is just the limit of Socket 7.

Some 440ZX motherboard, like the ASUS P2-99B with a Celeron 300A (overclocked to a 100 MHz FSB = 450 MHz), would be way more interesting in terms of performance.
https://theretroweb.com/motherboards?page=1&i … tIds%5B0%5D=287

But let's be honest, the popularity of the K6-2/3 was born from the rather nutty idea of getting an all-in-one PC that could run everything "from DOS to Windows XP".

I can only install a board that's maybe one inch longer than the ISA slots, unless everything beyond that is really short.

If you know a more advanced Baby-AT motherboard that might fit, I'm all ears. 😀

Lylat1an wrote on 2026-08-22, 05:30:

shevalier wrote on 2026-08-22, 04:05:

Some 440ZX motherboard, like the ASUS P2-99B with a Celeron 300A (overclocked to a 100 MHz FSB = 450 MHz), would be way more int […]
Show full quote

Ozzuneoj wrote on 2026-08-22, 03:08:

Absolutely... there is no point in doing that for such a small performance bump. Just spitballing, but that $350 unicorn of a CPU is only ~30% faster than what you have in the best case scenario.

This is just the limit of Socket 7.

Some 440ZX motherboard, like the ASUS P2-99B with a Celeron 300A (overclocked to a 100 MHz FSB = 450 MHz), would be way more interesting in terms of performance.
https://theretroweb.com/motherboards?page=1&i … tIds%5B0%5D=287

But let's be honest, the popularity of the K6-2/3 was born from the rather nutty idea of getting an all-in-one PC that could run everything "from DOS to Windows XP".

I can only install a board that's maybe one inch longer than the ISA slots, unless everything beyond that is really short.

If you know a more advanced Baby-AT motherboard that might fit, I'm all ears. 😀

After all, a standard Baby-ATX is 220mm. Is it truly impossible to fit even the PCPartner ZXB860S (35-8850)?
https://theretroweb.com/motherboards/s/pcpart … zxb860s-35-8850
This motherboard does exist, but it is no longer available anywhere.

https://theretroweb.com/motherboards?manufact … tIds%5B0%5D=508
https://www.ebay.com/itm/125347812346
https://www.ebay.com/itm/125436440376
https://www.ebay.com/itm/236727125616
PS The prices you've got on eBay are ridiculous...

Lylat1an wrote on 2026-08-21, 10:54:

https://seasonic.com/core-gx/#specifications […]
Show full quote

https://seasonic.com/core-gx/#specifications

I have the 650w version, actually.

20 watts for the 3.3 and 5 volt outputs, 100w combined.

I'm guessing that isn't bad considering it's "modern" ...

^ That's an excellent modern PSU for retrocomps. Quality internals, with jap caps all around (including some polys on the minor rails).

The fan spins at a decent rpm in the crossload conditions typical of retrocomps (heavy +5V & +3.3V, light +12V), keeping things cool:

DC-DC for the minor rails (= good voltage stability), with an aluminum plate heatsink cooling their FETs:

And de facto you can pull ~25A from every minor rail before OCP triggers:

Seasonic Core GX Series 500 W Review

shevalier wrote on 2026-08-22, 06:23:

https://theretroweb.com/motherboards?manufact … tIds%5B0%5D=508 https://www.ebay.com/itm/125347812346 https://www.ebay.com/itm/1 […]
Show full quote

Lylat1an wrote on 2026-08-22, 05:30:

I can only install a board that's maybe one inch longer than the ISA slots, unless everything beyond that is really short.

If you know a more advanced Baby-AT motherboard that might fit, I'm all ears. 😀

https://theretroweb.com/motherboards?manufact … tIds%5B0%5D=508
https://www.ebay.com/itm/125347812346
https://www.ebay.com/itm/125436440376

The two listings I kept might be worth looking into, though the RAM slots might be right against the drive bay.

What would be a good CPU to pair with these?

shevalier wrote on 2026-08-22, 06:23:

PS The prices you've got on eBay are ridiculous...

I know of that seller, his prices do tend to be on the high side.

Lylat1an wrote on 2026-08-22, 11:09:

shevalier wrote on 2026-08-22, 06:23:

https://theretroweb.com/motherboards?manufact … tIds%5B0%5D=508 https://www.ebay.com/itm/125347812346 https://www.ebay.com/itm/1 […]
Show full quote

Lylat1an wrote on 2026-08-22, 05:30:

I can only install a board that's maybe one inch longer than the ISA slots, unless everything beyond that is really short.

If you know a more advanced Baby-AT motherboard that might fit, I'm all ears. 😀

https://theretroweb.com/motherboards?manufact … tIds%5B0%5D=508
https://www.ebay.com/itm/125347812346
https://www.ebay.com/itm/125436440376

The two listings I kept might be worth looking into, though the RAM slots might be right against the drive bay.

What would be a good CPU to pair with these?

https://theretroweb.com/motherboard/manual/58 … ca966726104.pdf
I have no idea.
It’s a PCPartner motherboard with VIA chipsets.They are very weird and cheap.
Theoretically, it could support a Pentium 3 Coppermine at 1GHz with a 100MHz bus.
Practically, these PCPartner boards have a terribly broken BIOS—so bad that the memory speed feels like a Pentium 1 MMX.
Luckily, there's the BIOS Patcher utility, which fixes up their sloppiness a bit.

Long story short, this is not high-end (or even mid-range). So it's best not to bother looking for a super-fast CPU for it.

shevalier wrote on 2026-08-22, 17:29:

Long story short, this is not high-end (or even mid-range). So it's best not to bother looking for a super-fast CPU for it.

In that case, it might be best to enjoy what I have for now, and try a rebuild another time.

Thank you!