Also, as another thing: it appears that that motherboard has a cache slot to the right of the CPU. Does anyone know where I could get some cache for this system and how much of an improvement I should expect?

Ahhh! Almost the same make and model as my childhood Presario 4766!

Here is the thread with my build:
My Compaq Presario 4766 - DOS / Win9X machine

You have a S3 Trio64V+ with only 1MB I see, but it can be upgraded. 80MB SDRAM is the limit unfortunately. I'm a bit shocked to see your computer being delivered without a COAST cache module. You can buy these on Ebay, get a 512kb one for 1-2% extra speed over a 256kb one.

The machine/board/bios supports AMD K6 CPUs. I'm running an AMD K6-III at 400mhz in my system and I highly recommend getting that over a K6-2. It gives a huge performance boost, see my benchmarks in the thread I linked. Be aware you need an original AMD K6-III, not the + model, that won't work. The adapter should set the correct voltage for the AMD K6 (that is why it requires power) and it should have a clip so it can be attached to the board. Looking on your pictures it seems it is missing so you'll have to be creative I guess.

Nice OEM machine. 😀

I have one of those except the CDROM is a slot loader. Only machine I have with a bigfoot hard drive.

I'm not familiar with that specific model, but I have something similar, Preasrio 4504 (though it may technically be a little higher as to get over the 48MB RAM limit I swapped the main board out for a later model in order to get 64MB)

Good on you for replacing the Bigfoot, when I first saw that thing I didn't even know hard disks could get that...physically huge.

Anyway, you lucked out, mine only has one pci slot, and it's shared with one of the three isa slots. And to my luck it absolutely hates my nifty usb 2.0/NIC card...

I don't know what you should do about CPUs, but I managed to get mine to a MMX 233Mhz, from a 200MHz Pentium..without MMX... I tried to get various K6 Cpus to work, but it refused to boot with them. You can try the adapter, but your mileage may vary.

That slot is indeed for cache, COAST (cache on a stick) It took me forever to figure that out, almost no info on it unless you know exactly what to look for. It was hard to find any for sale, I bought two, the only two I could find, because apparently compatibility is sketchy. One was 256KB the other 512KB, 256KB is detected and works fine, but naturally, the larger and more desirable one did not.

Over the years I've played with it on and off. Attempting to get an old SB16 to work (I failed) Using Windows 98 and or 95, didn't work out very well, now windows gets corrupted every time I try...) Linux (only Damn Small Linux works to any extent) and FreeDOS (but I'm too young to know how to use it beyond really simplistic file navigation...and file transfer is a b****.

Anyway, I don't know why mine began to hate windows so much, but you may want to limit OS experimenting, if you can get Win9x installed, keep it installed. Some drivers are still on HP's website last I checked.

Alright! I've managed to fix the whole CPU fan sliding off situation in the form of lots and lots of rubber bands 🤣

As for the cache RAM, I've managed to find something on ebay:
http://www.ebay.com/itm/512KB-Cache-SRAM-Coas … K-/281071267546

Would this be it? I'd also like to know what, exactly, it should do for overall performance. My guess is that it should help make up for the painfully slow 66MHz system bus. As another question, at what speed does this cache run relative to the CPU itself? On the Wikipedia page for the K6-III, it says that combined with some on-board L3 cache, the K6-III (though mine is a 2) was competitive with the Pentium III Katmai.

I've managed to run some benchmarks in the current setup. Below are some speedsys scores:

Pentium 200 MHz (I picked out the relevant scores):
CPU speed index : 148.35

Total memory size : 80 MB
Memory speed index: 168.11

Cache/Memory Benchmark
³ Read ³ Write ³ Move ³ Average ³
³ Cache Level 1 ³ 255.23 MB/s³ 85.07 MB/s³ 763.20 MB/s³ 367.83 MB/s³
³ Memory ³ 101.68 MB/s³ 85.02 MB/s³ 69.77 MB/s³ 85.49 MB/s³

MMX(tm) Cache/Memory Benchmark
³ MMX Read ³ MMX Write ³ MMX Move ³ Average ³
³ Cache Level 1 ³ 446.02 MB/s³ 170.13 MB/s³ 231.84 MB/s³ 282.66 MB/s³
³ Memory ³ 126.60 MB/s³ 169.88 MB/s³ 69.77 MB/s³ 122.08 MB/s³

For the K6-2 400MHz (Once again, I picked out relevant scores from the SSTREP file):
CPU speed index : 451.80

Total memory size : 80 MB
Memory speed index: 168.11

Cache/Memory Benchmark
³ Read ³ Write ³ Move ³ Average ³
³ Cache Level 1 ³ 1437.72 MB/s³ 64.09 MB/s³ 1336.64 MB/s³ 946.15 MB/s³
³ Memory ³ 202.66 MB/s³ 64.03 MB/s³ 69.77 MB/s³ 112.15 MB/s³

MMX(tm) Cache/Memory Benchmark
³ MMX Read ³ MMX Write ³ MMX Move ³ Average ³
³ Cache Level 1 ³ 2106.89 MB/s³ 127.95 MB/s³ 1114.98 MB/s³ 1116.60 MB/s³
³ Memory ³ 202.66 MB/s³ 128.08 MB/s³ 69.77 MB/s³ 133.50 MB/s³

Is there any reason for the really slow memory write speeds on the K6? It looks like there may be some sort of cache problem there...

Now for some Quake 1 benchmarks (using timedemo demo1):
Pentium 200:
800x600: 11.2 fps
640x400 (accidentally clicked this instead of 640x480): 18.8 fps
320x200: 45.8 fps

K6-2 400:
800x600: 11.7 fps
640x400: 19.7 fps
320x200: 50.2 fps

While there was a clear bottleneck at 800x600, the 320x200 benchmark kind of surprises me. I'd expect a CPU that gets a 3.04x better SpeedSys score would be a bit faster than that. Could the slow write speed be a bottleneck?

Also, one part of the SpeedSys report that I neglected to mention for the K6-2 says:
Write Allocate : Disabled

What does that mean? Does it have something to do with this? Am I asking too many questions? AAAAH?

Yes, that COAST module you linked to on Ebay will work. I have the same one (bought from the same seller) and it works in the Compaq.

There are not that much difference between a K6-II and a Pentium 200 in this system. You are hampered by the 66mhz bus and slow cache. Highly recommended to get a AMD K6-III as the L2 cache is the on the CPU (I have more benchmarks on this system, check Phil's VGA Benchmark for Quake/3DBench/PCPBench/Doom)

The S3 chip is a Trio64V2/GX which is the latest non-3D chip made by S3, same date as ViRGE/DX or /GX. Not that it matters which chip it is exactly. Very good compatibility for DOS. I don't know if the 1MB VRAM slows it down, that could happen with some graphics chips. As vetz said, upgrading the VRAM is an option (the two sockets next to the VGA connector). For Quake or DN3D you should probably install a VESA 2.0 TSR (unless the video BIOS includes that which is probably not the case). S3VBE20 should do the trick.
If I understand correctly the board doesn't have any cache at the moment. Even if you add cache (which will run at the 66 MHz FSB) the Intel VX chipset will only cache the first 64 MB. I suppose even Win98 would run better with only 64 MB instead of 80 MB. (I think it is possible to install 80 MB and tell Windows to only use 64 MB if that is easier for you.) If you install a K6-III the mainboard's cache won't matter anymore (at least not very much). For DOS the installed 48 MB should be fine anyway.
Do you know if the CPU adapter can also provide 2.0V? A K6-III+ might be easier to get than a K6-III, and although BIOS support is nice missing support can be worked around. See http://web.inter.nl.net/hcc/J.Steunebrink/k6plus.htm and http://web.inter.nl.net/hcc/J.Steunebrink/S1590-K6-III+.htm

Write Allocation is important for performance. A K6-2 400 should have this feature. It has to be enabled by the BIOS or an additional utility, though. Your BIOS doesn't seem to do this which is understandable since the board doesn't deliver the necessary voltage anyway.
Write combining for writes to video RAM is also important. I don't think that a BIOS would enable write combining, you'll either have to use a utility, or if you are lucky the video driver will enable WC in Windows.

Regarding the Mystique: Although it technically can do accelerated 3D, I wouldn't use it for Direct3D games, only for games that are adapted for Matrox's proprietary MSI API. See 3D Accelerated Games List (Proprietary APIs - No 3DFX/Direct3D) for more information. A good option would be a Voodoo1/2 (obviously), but something like a Riva 128 would also be a good match. The question is, which cards are available for you and will work with the board.

Just to add to the BIOS upgrade possibilities on AMD K6-III+. It is not possible as far as I know. It uses something called a RomPAQ BIOS which is not "updatable/hackable" through the means posted on those sites.

Write Allocation, no idea if its enabled. No option in the BIOS for it. But looking at the VGA benchmarks on Phil's database its not very high compared to a real SS7 system. Its on par with other Socket 5/7 systems though which has the AMD K6-III:
ASUS PCI/I-P54TP4 Socket 5 motherboard thread/review

There are not that much difference between a K6-II and a Pentium 200 in this system.

To be fair, this is only in the benchmarks that I have run (namely quake... and nothing else 🤣 )
Tonight I'll try more benchmarks like Duke3d and DOOM if at all possible and report back. I'm hoping for something close to the somewhat disappointing 98.7 fps that the 686 benchmark comparison has a similar CPU pegged at in DOOM. The Pentium should get around 82 fps for comparison.

About the quake scores: To be honest, after looking at the Ultimate 686 Benchmark Comparison and re-running the timedemo at 640x480, I found that my scores are about on par for the course:

My system: 16.8fps
A k6-2 with 66MHz FSB: 17.2fps
A k6-2 with 100MHz FSB: 19.1fps 😲

It is true that the performance difference between this and the Pentium is kind of disappointing, but after researching it, Quake is one of the most, if not the most, Pentium-optimized games in existence.

Do you know if the CPU adapter can also provide 2.0V?

I'll check tonight. It may be possible, and if it is, I'm definitely going for the III+, just by virtue of it having lots of cache.

Write combining for writes to video RAM is also important.

For fun, I actually ran fastvid. Needless to say, it crashed, but it did come with the vspeed utility. To be honest, the results didn't seem too far off:
49.57 MB/s and 51.8 MB/s.

Regarding the Mystique: Although it technically can do accelerated 3D, I wouldn't use it for Direct3D games, only for games that are adapted for Matrox's proprietary MSI API. See viewtopic.php?f=46&t=33483 for more information. A good option would be a Voodoo1/2 (obviously), but something like a Riva 128 would also be a good match. The question is, which cards are available for you and will work with the board.

I basically picked out the Mystique because it's the fastest PCI graphics card I have available, and after a 30 second wikipedia search, I saw "3d acceleration" and thought, "Well, looks like I'm set!"

Just to add to the BIOS upgrade possibilities on AMD K6-III+. It is not possible as far as I know.

I did at one point install the newest ROMPaqs, but they were completely useless. I'll try it if I can get a K6-III+ for cheap enough. I don't see any reason why it wouldn't work, since I wouldn't expect either of our Compaqs to support more than a Pentium MMX.

Too bad there are no undocumented FSB settings as far as I can tell. Does anyone have a pinout of the chipset? It would be cool to see if there's a way around any of these limitations.

I've tested with a AMD K6-III+ in my machine and it does not boot, save yourself the money unless you get it for an euro 😀

Hm. That's a shame. It would've been nice to have an absurd amount of cache to make up for the RAM and bus speeds in that computer.

I managed to run a few more benchmarks including some somewhat unscientific ones:
For fun, I ran Chocolate DOOM on my desktop computer and laptop (running Linux Mint 17 and 16, respectively). The source port used was Chocolate DOOM at 640x480x32bpp, since my modern graphics cards don't support 320x200x8 (now that I think of it, I bet they could if I dug up my CRT...):
Laptop (2000 MHz A6-5200): 265.5 fps
Desktop (4600 MHz FX-8350): 663.8 fps.
The laptop was 5x faster in terms of clock rate and 3.6x faster in terms of frame rate (though running at 4.8x higher resolution)
The desktop was 11.5x faster in terms of clock rate and 7.66x faster in terms of frame rate (once again running at 4.8x higher res.)

Anyway, back to the actual benchmarks:
Doom framerate in Windows (k6-2):
86.6
DOS:
85.31... weird.
With integrated graphics (dos):
84.9 fps... huh.

Integrated graphics: (DOS, Pentium 200):
75.207 fps

Other graphics:
DOS: 77.87 fps
Windows: 75.036

Windows boot times:
Pentium 200 MMX: (power on to network password prompt, done twice and averaged): 65.74+66.27
66 sec average.

K6-2: 58.24+58.78,
58.51 sec avg.

Loading mail.google.com on Mozilla:
Pentium 200 MMX: (2 times and averaged): 23.71 +23.58 sec. 23.645 avg.
K6-2 400: 18.59 + 17.55 sec. 18.07 sec avg.

Vogons.org main page:
Pentium 200 MMX: (2 times and averaged): 12.24 + 12.05 sec. 12.145 avg.
K6-2 400: 10.51 + 10. ~10.25 sec avg.

meisterister wrote:

Hm. That's a shame. It would've been nice to have an absurd amount of cache to make up for the RAM and bus speeds in that computer.

The AMD K6-III non plus have the same amount of cache and performance. Its not like you're going to overclock more either as maximum speed is 400mhz.

meisterister wrote:

Write combining for writes to video RAM is also important.

For fun, I actually ran fastvid. Needless to say, it crashed, but it did come with the vspeed utility. To be honest, the results didn't seem too far off:
49.57 MB/s and 51.8 MB/s.

FASTVID is only for PPro/PII/PIII, not for K6-x. Try one of these tools: http://www.k6plus.com/phpBB3/dm_eds/showcat.php?id=3 (or setk6).

meisterister wrote:

Too bad there are no undocumented FSB settings as far as I can tell. Does anyone have a pinout of the chipset? It would be cool to see if there's a way around any of these limitations.

Intel VX doesn't support other PCI dividers so if you overclock the FSB to eg. 75MHz you'll overclock the PCI bus slightly. Usually that's not a problem, though.

Just posted my presario 4784 sleeper. Not done with it yet but I think you presario fans might like it. Something you dont see everyday...
https://imgur.com/gallery/A65Kn

And yet another great Compaq machinery, they are the best right after IBM......