I mostly play around with Super Socket 7 boards... the past week I've run it with Intel P-MMX 266@350Mhz and AMD K6-3+ 400@600Mhz. Would try going higher but the board only supports 100Mhz FSB - need another compatible board 😉

Well to be honest,I suspect most people here are gonna tell you Intel Pentium MMX, and that is fair, especially if your going to want to play quake as well as it can be on the platform(Quake was hand coded for the Intel Pentium FPU and performs far better on the intel part because of it, and as Quake is easy to benchmark because of the built in FPS counter and was a very popular game of the time it became the benchmark on the platform). Now I'll hold my hands up here, I don't like Quake, I just don't enjoy the gameplay and frankly I think it looks bland and horrible,oh look more brown...... so it's never been a driving factor for my builds.
For pure integer performance both the Cyrix 6x86 and the AMD K5 are the faster and to my mind more interesting parts. The IPC on both are better than the Pentium. Even the Winchip C6 is faster at integer programs than a rating comparable Pentium.(C6 also is a very cool running chip, I used one for years back in the late 90's early 2000's in my dedicated MSword 6 machine, it was flawless).
My intel TX system has a AMD K5 PR-166(it actually runs at 117MHz!), when I first built it I tried a ton of socket 7 CPU's, Pentiums, MMX's, Cyrix 6x86/6x86L,6x86MX, MII, Winchip C6 200, AMD K6 166 even a AMD K5 SSA/5 75MHz and the CPU I liked the best was the K5 166. I was just a nice fit for what I was running and was a interesting and more unusual choice, been in the system now for 5 years+. I use Dos 6.22 and Windows 3.11, if your planning on Windows 98 or something then I guess it's perhaps better to look elsewhere for a CPU, although the intel TX isn't going to be great on Win 9x anyway with the 64MB RAM cache limit.
I use Cyrix MII PR 333 in a faster SiS based socket 7 machine and a AMD K6/2 450MHz(100 MHz FSB) in a SiS Super 7 machine, these are much better suited to Windows 9x not least because they can cache more RAM than the TX board can. If I need something faster for 9x I go to the awesome AMD Duron "Spitfire", one of my all time favourite CPU's(these were just so good at the time, best buy CPU of the era by a country mile I reckon).
Anyway, if you can find the CPU's at a price your happy with I see no reason not to go Pokemon and "catch them all!"(speaking of which, I've been playing Pokemon Crystal on visual boy advance emulator on the Cyrix MII machine a ton recently!). I really enjoyed exploring all these different chips and seeing the pluses and minuses of each. You could even try to track down a RiSE MP-6 CPU, they were only really sold in Asia as far as I can tell and despite the fact I live in Japan 50% of the time I've not tracked down a working one yet even in Akihabara district. They seem to be VERY fragile sadly, all the ones I have had are dead.
Anyway, sorry this has been so long, enjoy your new machine!

Pentium MMX
Obvious "go to" choice for S7 platform. Performance can be gracefully toned down to desired speed. Also available as mobile version, which you can crank up to 400+ Mhz, but requires specific boards to works and some physical tweaking for L2 to work.

Classic Pentium
Less interesting, but still solid choice and can work on any board without any hassles, unlike some third-party CPUs.

AMD K5
Early models are garbage with hardware bugs, but late gold top ones fixed some issues and very capable at integer calculations. Still, they are somewhat power hungry, which limits motherboard choices, and barely can compete even with classic Pentium 166 due to MHz bottleneck. Not practical.

AMD K6
Completely obsolete and probably even harder to find than K6-2. Not practical.

AMD K6-2
Another "go to" choice. Good compatibility with boards (can work even on Intel motherboards). Late models can compete with Pentium MMX with sheer MHz power in unoptimised FPU related tasks and integer performance is just better, although not on K5 level.

Cyrix 6x86
Depending on revision, might not be even compatible with some software. Can be capricious with boards. Later MII is decent CPU, but no match to PMMX and AMD K6-2. Early 6x86/6x86MX - not practical. MII - usable, but would be at the bottom of the list of choices.

IDT WinChip C6
The slowest CPU for Socket 7. It's basically pumped up 486DX, if one had wider bus, MMX instructions and huge L1 cache. Can be useful to recreate "486 experience" on much more accessible platform. Also can work on anything, probably because it was designed and promoted as an upgrade for really old machines. Practical? Not really, but has a niche use.

I personally liked the AMD K5 (later gold top versions). I remember being really surprised how well it ran FPU-heavy tasks, it even played Quake 3 at reasonable frame rates. Seems to punch way above its weight and it's also a rarity.

There are a few issues of Byte with great coverage of those 90s CPUs
https://archive.org/details/eu_BYTE-1994-11_OCR
https://archive.org/details/eu_BYTE-1995-11_OCR

Don't forget the K6-2+, which is a K6-III but with half the cache and a lower voltage. There are quite a few available on eBay. I upgraded my HOT-591P which had a PMMX 233 from back in the day to one of these.

jakethompson1 wrote on 2020-07-16, 18:55:

Don't forget the K6-2+, which is a K6-III but with half the cache and a lower voltage. There are quite a few available on eBay. I upgraded my HOT-591P which had a PMMX 233 from back in the day to one of these.

Pretty expensive on eBay though. For that price I can get more RAM and a new GPU for a super socket 7 system which would benefit performance more than a + model CPU.

this is all great info - thank you

brian105 wrote on 2020-07-16, 22:41:

jakethompson1 wrote on 2020-07-16, 18:55:

Don't forget the K6-2+, which is a K6-III but with half the cache and a lower voltage. There are quite a few available on eBay. I upgraded my HOT-591P which had a PMMX 233 from back in the day to one of these.

Pretty expensive on eBay though. For that price I can get more RAM and a new GPU for a super socket 7 system which would benefit performance more than a + model CPU.

As with everything: patience!

I have a K6-2+ and a K6-3+ bought in the last few years, both bought on eBay, both bought for EUR 15. Keep a sharp eye out and good buys do pop up.

IF you're going to judge merits, don't forget to take their original selling prices into the factor. Pentiums were expensive luxuries, and it's easy to forget that in 20XX without context and think all the other CPUs are a waste and get narrowly judged with quake not providing enough bungholiomarks for the software renderer.

K5 is a very nice option if you like older games.

leileilol wrote on 2020-07-17, 22:32:

IF you're going to judge merits, don't forget to take their original selling prices into the factor. Pentiums were expensive luxuries, and it's easy to forget that in 20XX without context and think all the other CPUs are a waste and get narrowly judged with quake not providing enough bungholiomarks for the software renderer.

That's a good point. This isn't original selling price but for curiosity's sake I found a CPU ad in the February 1998 PC Magazine.
Some of the pricing is: PII @ 300 - $799, PMMX233 - $329, K6-233 - $269, P133 - $99, and a 486DX4-100 was $39.

So comparing the situation in early 1998 to now, it's roughly PII - Core i9 (or Xeon?), P233 - Core i7, K6-233 - AMD Ryzen 5, P133 - Core i3, and 486DX4 - Celeron.
Of course, inflation means those old processors cost even more than it looks.
You can see how tempting the K6-2 and K6-III were once they came out given the high price of the Pentium II.

Don't forget the IDT Winchip 2, also with 3DNow! instructions and Socket 5 compatibility.

I asked this in another thread and got no reply so I guess I may as well ask it here as well. How well can K6 and K6-2 processors be slowed down? How slow do they get after disabling L1/L2/L1+L2 cache? I believe some games like Ultima 7 override SETMUL L1D for Pentium CPUs but not L1DX, is this command usable for K6/K6-2 CPUs?

As far as I remember AMD K5/K6 processors is not the best choice for very old games.

There are old games that calibrate timers using idle loops. These are heavily optimised on AMD CPUs. More than on other CPUs like Pentium. Thus some of these games run too fast or fail.

My favourites on s7:

K6-3+ 400 @500 (not need for 600 or more, keeping stress a bit down).

MMX 200, running 100x2,5. A little bit of cheating with a Super7 board.

I have most Pentiums above 133MHz and several MMX 200s, some Cyrix (IBM 6x86 and cyrix mII) and a few K6/K6-2/K6-3 laying around, but I don't like them as much as these mentioned above.

For a 66MHz bus I probably would go for a K6-2 @66x6 or the good old P54c.

K6-III + and K6-2+ pretty much trump all when it comes to being slowed down and running at full clock.
There have been many threads on this, as well as Phil's excellent "Time Machine" builds....

Lostdotfish wrote on 2020-07-16, 10:15:

I was wondering what the general thoughts and consensus is around Socket 7 processors? I've built a system around an Intel 430TX Socket 7 board with a fairly diverse compatibility with chips of this era. (60MHz bus 1.5x - 3x | 66MHz bus 1.5x - 4.5x | 75MHz 2x - 3x)

I'm running a Pentium MMX P55C 200MHz in the system at the moment and I've just bought a K6-2 300 and a 75MHz bus Cyrix 6x86 PR200 to have a play around with (they popped up cheap). I'm interested to see how these other CPUs effect performance overall, especially to see how that K6-2 stacks up against the Pentium.

Is there much use in picking up some of the slowest processors on the list (Pentium 90, K5 100) to try and pull performance down for games that are speed sensitive? Any other merits of any of the given processor brands (IDT Winchip for novelty sake). What Socket 7s are you running and what are your experiences with them? I'm resisting the urge to go Pokemon on them... (gotta catch em'all)

I suppose you're referring specifically about Socket 7, and thus not Super Socket 7? In any case, I'm going to try and take the full range into account going from Socket 5 to Super Socket 7 as in my opinion making this distinction is kinda arbitrary from a practical viewpoint.

In my opinion, the most obvious choice to go for would be the Pentium MMX due to its excellent compatibility (with both software and hardware), excellent stability, good availability and usually good overclockability (so an accidental overvolt is less likely to kill it). It's basically the idiot-proof option.
Pentium without MMX should also work and has the added benefit of not being split voltage so it may play nicer with certain older boards (though these boards will probably be of the Socket 5 variety). This advantage is fairly minimal though and then there's also the MMX Overdrives along with other upgrade options.
K6 (and especially the first variety that ran at around 2.9v to 3.2v) are more a curiosity. There is a K6 made with the 25 micron process which should be much more useful, though there's little reason to not pick a real K6-2 over this somewhat more uncommon and lower clocked chip.
K6-III is a different beast, but seems to be not easy to find. The K6+ chips (which I regard to be all the K6-2+ and K6-III+ including the embedded E versions) are the best performers on the (s)s7 platform, but may take a bit more effort to get going.
Then there's also that Tillamook. Good luck getting that one going on whatever board you picked beforehand, it can be quite the project compared to the previously mentioned Intel and AMD options. I wouldn't recommend it if you're new, just go with a K6-2 instead.

Then there's the CPUs that are a bit more niche. Some of these may be useful in some niche and some may be basically suitable for perhaps a couple benchmarks and not much more.
The Cyrix chips probably fall in this category, though I tend to kinda want to like their later iterations (the lower voltage MII chips, even though I believe the Cyrix M2 300 (running at 233MHz) may also have a place here, if only due to its features despite it having, to some degree, similar issues that the K6 was also having). The Cyrix MII CPUs with lower voltage are more useful though, though may be a bit more difficult to set up. But come on, running linear burst has a nice ring to it right? 😜
From here it gets more and more obscure as we start moving into Winchip/Rise mP6/K5/Overdrive territory.

I probably left out a couple bits. But in short (and in my opinion), the most practical (easiest to work with and most idiot proof) chips will probably be the Pentium MMX and the K6-2 (non-plus). Second tier (or should I say, tier 1b?) is K6-III, k6+ and Pentium non-MMX. Rest is more adventurous which doesn't necessarily mean you should avoid them at all cost. Virtually all of these chips have something interesting going for them even if some of these options may seem like total crap at first sight 😜
Cyrix MII and Pentium Overdrives have their own peculiarities, but should work after a little bit of tinkering.

Now if you want pure brute raw performance, then K6+ is the way to go. The only chips that (may) come close are the K6-III (non-plus) and the Tillamook (if it works with L2 cache). Or perhaps even a vastly overclocked Pentium MMX chip (yes this is actually within the realm of possibility, though forget about getting 550MHz with sucha chip). The top dog Cyrix MIIs might be able to get kinda near a higher end Pentium MMX but at this point we're maybe talking about something like ok-ish K6-2/400 performance or something (but I wouldn't get your hopes up on either Pentium MMX and Cyrix MII coming close to 550MHz K6+).

Maybe it's getting time I share a few of my testing results here...

Still work in progress. More boards and CPU's to test, more combinations, more of everything.

If you miss any hardware combo of what's listed in here, please let me know and I can add it to the list of I got the hw (and when I find the time to do it).

https://www.dropbox.com/s/ioend0p7iildd0e/PC% … 0benchmark.xlsx