AFAIK this behaviour is to be expected on a Pentium 4. The Pentium 4 is at 2GHz to 3Ghz in hardware. There are no reliable software tricks to get that to a smooth 100MHz or something of that kind. At best one can disable CPU caches and see what kinda speed it seems to resemble. In the end, if you really want to run such DOS games nicely, without emulation, you need to consider slower systems and different tools and tricks.

Does Throttle work on your motherboard?
http://www.oldskool.org/pc/throttle/DOS

(And at the risk of asking a stupid question: is there some reason you want to run these in DOS on a Pentium 4 instead of in DOSBox?)

Yes, the reason is that I'd rather have 1 physical computer that runs multiple generations of games instead of 2 or 3. If it comes to having to experiment with other types of software to get the same effect I'll definitely do that, however I'd rather stick with this configuration unless i know definitively that it isn't possible to slow a P4 adequately.

Jorpho wrote on 2020-02-10, 19:17:

Does Throttle work on your motherboard?
http://www.oldskool.org/pc/throttle/DOS

(And at the risk of asking a stupid question: is there some reason you want to run these in DOS on a Pentium 4 instead of in DOSBox?)

Thanks, I'll definitely try one of those tools. And to be fair, there's no tangible particular reason I'd want to run these in DOS as opposed to Dosbox, but then there's no reason to use a CRT anymore or a chunky keyboard, or to own any particular console. So not sure what to say other than it's a project I guess.

gerwin wrote on 2020-02-10, 19:00:

The Pentium 4 is at 2GHz to 3Ghz in hardware. There are no reliable software tricks to get that to a smooth 100MHz or something of that kind.

Of course there are:

CPU Tuning, Throttling

Revolter wrote on 2020-02-14, 14:38:

Of course there are:
CPU Tuning, Throttling

Admitted, I missed that throttling functionality of the Pentium 4. Will look into it when I have some time.

gerwin wrote on 2020-02-14, 14:48:

Admitted, I missed that throttling functionality of the Pentium 4.

Believe me, this is normal - nobody seems to, for some reason. This is a mystery to me, since I think that throttle.exe and msred.com (together or separately) are supposed to be a small miracle and a revolution of the retro-PC scene. But nope, goes completely under the radar 😀 I was surprised to even see a mention of the chipset throttling in this particular thread.

I know about 'Throttle'. I even modified that program to make it work on ALi Aladdin V chipsets. Throttle is nice to have as an option, but for many games and programs it does not give smooth results: Stutters in framerate and sound output.

It is msred.com that is new to me.

gerwin wrote on 2020-02-14, 15:09:

I know about 'Throttle'. I even modified that program to make it work on ALi Aladdin V chipsets. Throttle is nice to have as an option, but for many games and programs it does not give smooth results: Stutters in framerate and sound output.

It is msred.com that is new to me.

I see. Glad to have been wrong about you, then 😀

Could it be that the stutters and uneven framerate are only present on non-Intel chipsets? I mean, does it produce the same results for you on any Intel board? I've tried a couple of VIAs (with 686B and 8237A) - yes, the performance is often messed up (and, when skipping 87.5% of cycles, the input signals of mouse and keyboard go kaput) - but have seen none of these problems on multiple boards with ICH2 and ICH5 southbridges.

Here is my observation on Throttle, back in 2009, on an i440BX system:
(edit: Darn, seems my final verdict there was based on the VIA system)
Re: Slowing a 440BX based PC
Here is the observation of ux-3, Athlon XP system:
Slowing an Athlon based PC - PCI audio causes trouble

Thanks!

I'm impressed. 2009... Turns out it was me who was late to the throttling party 😀

Yeah, your verdict corresponds exactly to my experience with VIA motherboards. Even down to the Quarantine game where I first noticed the speed quirkiness. The Intel chipsets do not exhibit any of these problems, though, exept for maybe having Speesys and other synthetic stuff return nonsense results.

dumpsterac1d wrote on 2020-02-10, 18:22:

I'm also still getting runtime/frame errors when running other games, such as Monuments of Mars, regardless of the switch settings.

This should help you get rid of those runtime/divide errors, but the games (especially Dark Ages) might still run way too fast. You'll need my patching utility to use these patch scripts. Scroll to the top of the page, there's a link to it.