Shponglefan wrote on 2023-09-07, 02:05:

I'm been planning out an 'ultimate' DOS rig for awhile now and have been looking at various potential options for max performance for late 90s stuff with heavily throttling for 80s and early 90s.

A pentium MMX can reach 386 and 486 speeds with ease using the SetMul utility to toggle test registers and disable caches. Phil has a handy chart here and a full video on the subject here. I use a similar system for DOS gaming and it works quite well. That said, I've never tried going for 286 speeds on my MMX rig, and I'm guessing you'd need software slowdown methods like throttle or moslow for that. Not sure how well that would work out.

Also, note that even the MMX 233 is too slow for late 3D SVGA DOS games like Tomb Raider, Quake and System Shock. That is if you want to play them using software rendering at 640x480 or higher. You would need something like a P3 500 for smooth framerates there. But if you use a Voodoo card (where applicable) these games become much more playable on a pentium MMX.

I've settled on a K6-2+ 450Mhz for my DOS machine, but the slowest it goes is ~33Mhz 486 territory. That's with L1 and L2 cache off, and the lowest multiplier (using SetMul of course). I've had limited success using SetMul and then a slow down utility on top of it but those are troublesome and inconsistent in my experience.

I think you need to decide whether you want 286/386 speeds more than you want late 90's era SVGA stuff, it'll be hard to get both.

I haven't found many games that I can't play on my via C3. At it's maximum performance it's also somewhere around a pentium 3 @ 700mhz. It can also get down to an 8088 more easily than most if you like really old games. I like it. Kind of like dosbox with real hardware.

Pentium MMX is definitely more flexible in slowing down than K6-2+/ K6-3+. If you want to get Dos-only or Dos/early Windows (up to year 1997) system, it's the way to go. You can combine PMMX with Super Socket 7 motherboard and AGP video cards. I have such system and it is great for 1990-1997 period games.
I can't compare PMMX with C3, but I doubt C3 can be slowed down more than 386 speed because as far as I know C3's minimum multiplyer is 4. Though I can be wrong.
C3 is still more flexible than K6-2+/K6-3+ because of low performance per MHz and higher multiplyers than in K6s.

Aslo in theory you can try to use slow ISA video card for hardware slowing down you system even more but I never seen any tests for verifying efficiency of this method.

The C3 is the only thing that can handle everything from speed sensitive XT software up to VESA mode 3D games like Duke3D, so there is no competition here..

Interesting topic. I thought that K6 and K6-2 are more flexible than P-MMX in terms of raw CPU speed.

appiah4 wrote on 2023-09-07, 09:20:

The C3 is the only thing that can handle everything from speed sensitive XT software up to VESA mode 3D games like Duke3D, so there is no competition here..

Which core - Joshua, Samuel (2), Ezra(-T), Nehemiah...?

mothergoose729 wrote on 2023-09-07, 04:02:

I haven't found many games that I can't play on my via C3. At it's maximum performance it's also somewhere around a pentium 3 @ 700mhz. It can also get down to an 8088 more easily than most if you like really old games. I like it. Kind of like dosbox with real hardware.

This is exactly what I'm looking for. 😁

What specs is your particular build?

badmojo wrote on 2023-09-07, 04:00:

I think you need to decide whether you want 286/386 speeds more than you want late 90's era SVGA stuff, it'll be hard to get both.

The challenge of seeing what is possible is all part of the fun. 😉

Joseph_Joestar wrote on 2023-09-07, 03:02:

A pentium MMX can reach 386 and 486 speeds with ease using the SetMul utility to toggle test registers and disable caches. Phil has a handy chart here and a full video on the subject here. I use a similar system for DOS gaming and it works quite well. That said, I've never tried going for 286 speeds on my MMX rig, and I'm guessing you'd need software slowdown methods like throttle or moslow for that. Not sure how well that would work out.

I watched that video of Phil's a few times. Originally I was planning an AMD K6 2/3 build, but then that video had me considering the Pentium MMX build instead.

Then I started reading about the Via C3 and started down that road...

Getting down to 286 speeds would be the most ideal for my use, so I'll probably go the Via C3 route as it seems the best option for that.

Also, note that even the MMX 233 is too slow for late 3D SVGA DOS games like Tomb Raider, Quake and System Shock. That is if you want to play them using software rendering at 640x480 or higher. You would need something like a P3 500 for smooth framerates there. But if you use a Voodoo card (where applicable) these games become much more playable on a pentium MMX.

Yeah, for games like Quake and Tomb Raider I definitely play them with 3d acceleration. I have a Pentium MMX 200 build right now with a Voodoo card and it runs both those games decently.

My current plan is my two pending builds: one a 1997-era rig focused on early 3D acceleration, and one being the aforementioned ultimate DOS rig trying to cover the broadest possible range of gaming.

analog_programmer wrote on 2023-09-07, 10:17:

appiah4 wrote on 2023-09-07, 09:20:

The C3 is the only thing that can handle everything from speed sensitive XT software up to VESA mode 3D games like Duke3D, so there is no competition here..

Which core - Joshua, Samuel (2), Ezra(-T), Nehemiah...?

Nehemiah for sure. Roughly speaking, if you wish to see where your Nehemiah CPU lands when it come to 3D games, you can find the equivalent Pentium III or Athlon to a Nehemiah C3 by dividing the clock speed in half. I have a C3 1200 that I run at 1466 with 133MHz FSB, effectively it's on par with a PIII 733. Some games it may be closer to the 866 even, in others it may be closer to something a bit slower.

I'll have to do some reading on the C3 too, I know nothing about these. There's always more to discover in this hobby!

Shponglefan wrote on 2023-09-07, 11:50:

mothergoose729 wrote on 2023-09-07, 04:02:

I haven't found many games that I can't play on my via C3. At it's maximum performance it's also somewhere around a pentium 3 @ 700mhz. It can also get down to an 8088 more easily than most if you like really old games. I like it. Kind of like dosbox with real hardware.

This is exactly what I'm looking for. 😁

What specs is your particular build?

Via C 3 nehemiah.

Note some speed reference points (namely the 486 range) requires software slowdown tools. The C3 ezra doesn't have this limitation, but the trade off is it has at best 1/2 the floating point performance and it's maximum clock is also about 20% lower. The Ezra-T is more than capable enough for windows games up through about the year 2000 though.

https://docs.google.com/spreadsheets/d/1usQPR … bPaw/edit#gid=0

I have a gigabyte slot 1 board with a slotket adapter. You could also use a socket 370 board with a via chipsets. There will be pros and cons to both chipsets. My board is this one:
https://theretroweb.com/motherboards/s/gigabyte-ga-6bxc

For the best performance you would want a board that supports 133mhz fsb. This particular board is also able to set the FSB at run time, which is pretty cool. I have a bunch of scripts that use setmul/mo slow/ and a set fsb utility and I can just change my CPU speed on the fly to match whatever I am trying to do (very much dosbox on real hardware).

Garrett W wrote on 2023-09-07, 12:02:

Nehemiah for sure. Roughly speaking, if you wish to see where your Nehemiah CPU lands when it come to 3D games, you can find the equivalent Pentium III or Athlon to a Nehemiah C3 by dividing the clock speed in half. I have a C3 1200 that I run at 1466 with 133MHz FSB, effectively it's on par with a PIII 733. Some games it may be closer to the 866 even, in others it may be closer to something a bit slower.

Thank you for this info. I've never seen in live any socket 370 processor different from PIII or Celeron. VIA C3 seems like very interesting piece of hardware.

With the right components and software, a VIA C3 computer as an "ultimate" DOS computer is feasible.

I'm currently running a Nehemiah one with a slotket adapter on an ASUS P2-99 motherboard thanks to DenizOezmen's modded BIOS. In my experience, the performance is approximately close (if not, slightly better) to a PIII-750 and the trade-offs compared to an Ezra-T (faster FPU and SSE vs flexibility around 486 speeds and 3DNow!) are worth it and got to the point that it relegated my Socket 7 computer.