DoZator wrote on 2025-06-20, 19:14:

...
All that's left is to figure out a way to reset the multiplier to "40" under Windows XP (installed on the same PC, on a separate partition). CrystalCPUID, in principle, allows you to change the multiplier on a given processor (using the /Fxx parameter), but it hasn't been updated for a while, and it doesn't seem to fully support the 4th generation. It has some internal limitations that prevent the multiplier from exceeding a certain value (based on my rough estimates based on benchmarks, it's around "31"), even if you use the "/F99" parameter (which should theoretically increase the multiplier to its maximum allowed value). Unfortunately, I haven't found any other XP-compatible tools (CPUSPD doesn't officially support XP).

Older versions of ThrottleStop work with Windows XP. I have just shared a proven to work version of it (ThrottleStop_600) in another topic here:
Re: x86 microarchitecture benchmark (MandelX)

Falcosoft wrote on 2025-06-20, 19:35:

DoZator wrote on 2025-06-20, 19:14:

...
All that's left is to figure out a way to reset the multiplier to "40" under Windows XP (installed on the same PC, on a separate partition). CrystalCPUID, in principle, allows you to change the multiplier on a given processor (using the /Fxx parameter), but it hasn't been updated for a while, and it doesn't seem to fully support the 4th generation. It has some internal limitations that prevent the multiplier from exceeding a certain value (based on my rough estimates based on benchmarks, it's around "31"), even if you use the "/F99" parameter (which should theoretically increase the multiplier to its maximum allowed value). Unfortunately, I haven't found any other XP-compatible tools (CPUSPD doesn't officially support XP).

Older versions of ThrottleStop work with Windows XP. I have just shared a proven to work version of it (ThrottleStop_600) in another topic here:
Re: x86 microarchitecture benchmark (MandelX)

All right, I figured it out. In fact, my mistake was that I changed not only the multiplier to "8" in the BIOS, but also the "Uncore Ratio" to the same "8" (assuming that these two settings should change synchronously). However, this is not the case. As a result, the performance did not return to its previous level. In fact, there is no need to adjust the "Uncore Ratio" at all. I've returned the "Uncore Ratio" to its default value. In general, both "ThrottleStop" and "CrystalCPUID" (with the /F99 parameter) correctly return the multiplier to the "40" value, and the performance is now fully restored. And those of my assumptions that you quoted above, regarding "CrystalCPUID" - NOT TRUE (CrystalCPUID, when launched with the parameter "/F99", quite correctly returns the multiplier back to the value "40", in combination with this processor, which is confirmed by the readings "ThrottleStop" and benchmark results). The problem is completely solved. Thank you for your help.

Hi All,

Long time no see, hope all is well.

Attached is a spreadsheet that might be of interest to you. I used it to automatically look up the equivalent cpu according to the DOOM realticks when developing CPUSPD. It also has the results for some of the CPUs I tested and recorded.

Just plug in the DOOM realticks from your test into column L, and column M ("Equivalent CPU", blue) will look it up from the "Reference" sheet and show you the results. The "Reference" sheet contains the results posted by one member on Vogons (sorry it was too long ago and I've forgotten who). Note that DOOM can't really run on 286 and below so the realticks for those cpus are interpolated.

Cheers!

For K10 does this depend on Bios/MB or just the CPU? Was planning to put together a AMD build for 98/XP/7 with something like a Phenom II X4, but even for 95/98 Windows there are a number of speed sensitive games so even getting down to a Pentium 1 alone would make me happy. I'm leaning towards the Asus M5A97 since it's confirmed working with 98, its socket AM3+ but like I said, a Phenom II or even an Athlon II will be better if it can be slowed all the way down like in the screenshots a few pages back. Thanks.

AaronS wrote on 2025-07-11, 03:26:

For K10 does this depend on Bios/MB or just the CPU? Was planning to put together a AMD build for 98/XP/7 with something like a Phenom II X4, but even for 95/98 Windows there are a number of speed sensitive games so even getting down to a Pentium 1 alone would make me happy. I'm leaning towards the Asus M5A97 since it's confirmed working with 98, its socket AM3+ but like I said, a Phenom II or even an Athlon II will be better if it can be slowed all the way down like in the screenshots a few pages back. Thanks.

The ability to scale down CPU cores to even 100 MHz is a CPU feature and BIOS independent.

kalohimal wrote on 2025-06-26, 12:16:

Hi All, […]
Show full quote

Hi All,

Long time no see, hope all is well.

Attached is a spreadsheet that might be of interest to you. I used it to automatically look up the equivalent cpu according to the DOOM realticks when developing CPUSPD. It also has the results for some of the CPUs I tested and recorded.

Just plug in the DOOM realticks from your test into column L, and column M ("Equivalent CPU", blue) will look it up from the "Reference" sheet and show you the results. The "Reference" sheet contains the results posted by one member on Vogons (sorry it was too long ago and I've forgotten who). Note that DOOM can't really run on 286 and below so the realticks for those cpus are interpolated.

Cheers!

The attachment cpuspd test sheet.png is no longer available

The attachment cpuspd_test.xls is no longer available

Hi I just came across this thread recently and I want to say THANK YOU for this great program.

I'm finally able to run Interstate 76 exactly right on my P4 retro PC. I'm running Windows ME on a 3.4 Northwood and using your utility to set the CPU to Throttle 2 makes the game function exactly as it should.

Thank you again!

kalohimal wrote on 2020-06-02, 11:29:

Cheers, DW.

Hello Kalohimal

I want to thank you very much for your incredible work.
Yesterday I could play all speed sensitive games that I always wanted.
I have an AMD K6-3 / 400 (non plus) and SETMUL doesn't work well.
With your Tool I created 5 speed profiles, it works marvelous:

386.bat => cpuspd c1d c2d t3 ebd edd (Ultima 6, Dune2, Monkey Island 1 demo)
486.bat => cpuspd c1e c2d t4 ebd edd (Turrican2, Jazz Jack Rabbit, OMF 2097, Epic Pinball)
586.bat => cpuspd c1e c2d t5 ebd edd (Doom 1+2, Duke3D, TES1 Arena, TES2 Daggerfall, Settlers2)
P100.bat => cpuspd c1e c2d t6 ebd edd (will test whether it works with Magic Carpet)
P233.bat => cpuspd c1e c2e t7 ebd edd (Quake 1 runs ok, without cpuspd it runs fluently 😀

386.bat: only Prince of Persia 1 freezes after start, but this is ok, I can play it in a DOS Box.

I'm having some issues if anybody can help me. I can't seem to run this program well in pure DOS mode. My system hard locks on several games and I have to power it off/hit the reset button. I got one error that said something about a stack overflow, but that only popped up once and hasn't since. When I run this program on Windows 98, it runs great without any crashes on the same games that are crashing. Any ideas or settings I may need to change in DOS? My processor is Core 2 Duo.

whatamansion2 wrote on 2026-01-30, 16:28:

I'm having some issues if anybody can help me. I can't seem to run this program well in pure DOS mode. My system hard locks on several games and I have to power it off/hit the reset button. I got one error that said something about a stack overflow, but that only popped up once and hasn't since. When I run this program on Windows 98, it runs great without any crashes on the same games that are crashing. Any ideas or settings I may need to change in DOS? My processor is Core 2 Duo.

Can you provide more info about your hardware and what games you're having issues with? Quite a few DOS games don't like it when you have too much extended memory. Are you using sbemu for sound? I've used CpuSpd quite extensively on P4 and Pentium M machines in pure DOS without issues. Crashes are usually memory or sound related. What options are you trying with CpuSpd? I typically adjust the ODCM value or disable the cache. Adjusting the throttle value will sometimes mess with the joystick calibration (but you probably don't have a game port?). Adjusting the multiplier is also a good option if your CPU supports it. How much free XMS do you see when you type "mem"?

eliot_new wrote on 2026-01-25, 19:24:

I have an AMD K6-3 / 400 (non plus) and SETMUL doesn't work well. With your Tool I created 5 speed profiles, it works marvelous: […]
Show full quote

I have an AMD K6-3 / 400 (non plus) and SETMUL doesn't work well.
With your Tool I created 5 speed profiles, it works marvelous:

386.bat => cpuspd c1d c2d t3 ebd edd (Ultima 6, Dune2, Monkey Island 1 demo)
486.bat => cpuspd c1e c2d t4 ebd edd (Turrican2, Jazz Jack Rabbit, OMF 2097, Epic Pinball)
586.bat => cpuspd c1e c2d t5 ebd edd (Doom 1+2, Duke3D, TES1 Arena, TES2 Daggerfall, Settlers2)
P100.bat => cpuspd c1e c2d t6 ebd edd (will test whether it works with Magic Carpet)
P233.bat => cpuspd c1e c2e t7 ebd edd (Quake 1 runs ok, without cpuspd it runs fluently 😀

386.bat: only Prince of Persia 1 freezes after start, but this is ok, I can play it in a DOS Box.

Do these profiles work with any processor or are they only suitable for your AMD K6-3?

kalohimal wrote on 2024-02-08, 14:23:

It looks like AMD K10 is a very good platform for retro DOS gaming. These CPUs can be slowed down enough to 486 speed just by ma […]
Show full quote

It looks like AMD K10 is a very good platform for retro DOS gaming. These CPUs can be slowed down enough to 486 speed just by manipulating their multiplier and divisor and south bridge throttling becomes unnecessary. To slow down further, cache could be turned off to achieve 286 speed and slower.

Test hardwares:
Biostar N68S3+ v6 with: Athlon II X2 250, Athlon II X2 440, Athlon II X4 600e, Athlon II X4 640.
Gigabyte GA-770T-D3L with Athlon II X2 440.

Settings for Wing Commander 1 (about 486-133):
cpuspd pm0504xx

Hello, so I'm trying to slow down a Phenom II in an AM3+ board to around a Pentium 100, a few DOS games like Destruction Derby and Descent etc. are way too fast even if I use the most extreme settings:

cpuspd p3
cpuspd pm0004xx

It's still like a Pentium III 1Ghz, if I disable cache (cpuspd cd) everything is way too slow (even on p0 @ 3.6Ghz+).

Would I be better switching to an Athlon II?

AaronS wrote on 2026-05-12, 03:40:

Hello, so I'm trying to slow down a Phenom II in an AM3+ board to around a Pentium 100, a few DOS games like Destruction Derby a […]
Show full quote

kalohimal wrote on 2024-02-08, 14:23:

It looks like AMD K10 is a very good platform for retro DOS gaming. These CPUs can be slowed down enough to 486 speed just by ma […]
Show full quote

It looks like AMD K10 is a very good platform for retro DOS gaming. These CPUs can be slowed down enough to 486 speed just by manipulating their multiplier and divisor and south bridge throttling becomes unnecessary. To slow down further, cache could be turned off to achieve 286 speed and slower.

Test hardwares:
Biostar N68S3+ v6 with: Athlon II X2 250, Athlon II X2 440, Athlon II X4 600e, Athlon II X4 640.
Gigabyte GA-770T-D3L with Athlon II X2 440.

Settings for Wing Commander 1 (about 486-133):
cpuspd pm0504xx

Hello, so I'm trying to slow down a Phenom II in an AM3+ board to around a Pentium 100, a few DOS games like Destruction Derby and Descent etc. are way too fast even if I use the most extreme settings:

cpuspd p3
cpuspd pm0004xx

It's still like a Pentium III 1Ghz, if I disable cache (cpuspd cd) everything is way too slow (even on p0 @ 3.6Ghz+).

Would I be better switching to an Athlon II?

No, instead you have to use the proper commands to set the MSR's on your Phenom II 😀
Try this for 100 MHz:

1cpuspd p1
2cpuspd pm000425
3cpuspd p0
4cpuspd pm000425

But here is a BAT file that can be used to set different speeds from ~3 GHz to 100 MHz:

You can check if the proper speed is set with my TSCDOS utility:
https://falcosoft.hu/tscdos.zip

vico wrote on 2026-05-09, 16:20:

eliot_new wrote on 2026-01-25, 19:24:

I have an AMD K6-3 / 400 (non plus) and SETMUL doesn't work well. With your Tool I created 5 speed profiles, it works marvelous: […]
Show full quote

I have an AMD K6-3 / 400 (non plus) and SETMUL doesn't work well.
With your Tool I created 5 speed profiles, it works marvelous:

386.bat => cpuspd c1d c2d t3 ebd edd (Ultima 6, Dune2, Monkey Island 1 demo)
486.bat => cpuspd c1e c2d t4 ebd edd (Turrican2, Jazz Jack Rabbit, OMF 2097, Epic Pinball)
586.bat => cpuspd c1e c2d t5 ebd edd (Doom 1+2, Duke3D, TES1 Arena, TES2 Daggerfall, Settlers2)
P100.bat => cpuspd c1e c2d t6 ebd edd (will test whether it works with Magic Carpet)
P233.bat => cpuspd c1e c2e t7 ebd edd (Quake 1 runs ok, without cpuspd it runs fluently 😀

386.bat: only Prince of Persia 1 freezes after start, but this is ok, I can play it in a DOS Box.

Do these profiles work with any processor or are they only suitable for your AMD K6-3?

They work well on K6-3 non-plus 400Mhz AHX with 2.4 Volt.
CPUSPD refuses to deactivate 2nd Level Cache on K6-2 400 or K6-233, nor does it apply any throttling on ALi 5 Chipset.

This is the reason why I have now 2x K6-3 non-plus CPUs along with 2x ALi5 Boards (Asus and Acorp)
AFAIK K6-3 plus 400 CPUs with 1.6 Volt are also supported.

This means:
K6-2+ along with K6-3+ can use SETMUL as well as CPUSPD for throttling.
K6-3 nonplus can only use CPUSPD as it is not supported by SETMUL.
K6-2 nonplus can use something else, but I have no idea what?

Besides: I have left only 4 profiles:
386, (Prince of Persia 1.4 runs perfectly (all other editions 1.1, 1.2, 1.3 freeze) as well as Ultima 6, Falcon 3.0, Monkey Island 1: they run really ok)
486, (Jazz Jack Rabbit, Epic Pinball, OMF2097)
586 (Magic Carpet, Dungeon Keeper) and
686 (Quake 1 etc)

For all interessted people here: you can use a PCI card like Spea Mirage V7 along with an APG card on ALi5 board:
1. AGP: e.g. Rendition v2200 (connected to 1st Monitor, only for Win98SE or specifici Rendition DOS games)
2. PCI: Spea Mirage or other S3 Trio64 PCI card (disabled in Win98SE, VGA connected to a 2nd monitor)

Bios: INIT display first AGP/PCI vs. PCI/AGP
=> whenever you want to play DOS only games that cause conflicts on your AGP card, select PCI/AGP to play on the 2nd monitor

Falcosoft wrote on 2026-05-12, 06:41:

No, instead you have to use the proper commands to set the MSR's on your Phenom II :) Try this for 100 MHz: […]
Show full quote

No, instead you have to use the proper commands to set the MSR's on your Phenom II 😀
Try this for 100 MHz:

Copy code to clipboard

1cpuspd p1
2cpuspd pm000425
3cpuspd p0
4cpuspd pm000425

But here is a BAT file that can be used to set different speeds from ~3 GHz to 100 MHz:

The attachment RESETPWR.zip is no longer available

You can check if the proper speed is set with my TSCDOS utility:
https://falcosoft.hu/tscdos.zip

Okay thanks I understand now, I didn't realize I had to apply it to several "profiles" (p1, p0 etc.)

It's working well now but I'm now trying to use this with VSBHDA (loading a soundfont for General Midi port 330) however the game locks up. I'm assuming this is because it's using additional CPU as well as RAM to run this in the background which, if I just use Soundblaster for both SFX and music, it works fine. In the following case I'm testing Star Wars Dark Forces (this game is 99.9% fine but is speed sensitive on the ice level where, you can basically get stuck and move really slowly), anyway if I load only VSBHDA with only SoundBlaster SFX and music, it works fine and you can see I am able to move around on the ice @ 250Mhz, but then if I load a soundfont the game crashes even going up to 400mhz (too fast at this point as I get stuck). Not sure if you have tried cpuspd with VSBHDA soundfonts but I guess we can't have it all on these newer platforms 🤣 but I wanted to ask anyway

https://youtu.be/3l83_FHNOO4

For the record you can easily get passed this part of the game with a fast CPU you just need to get the ice cleats as soon as possible, but its a good level to test.

I tried cpuspd 2.2 on my core i7-2600k and successfully can set mul in range 16-45x (45 was set by me in setup as max turbo). Interesting that tools using TSC measure still the same freq but I can see how voltage changes. This CPU has some kind of invariant TSC, older CPUs measures different freq for different mul. What to use for real freq measurement here? Some perf.counter?

RayeR wrote on 2026-06-04, 11:56:

I tried cpuspd 2.2 on my core i7-2600k and successfully can set mul in range 16-45x (45 was set by me in setup as max turbo). Interesting that tools using TSC measure still the same freq but I can see how voltage changes. This CPU has some kind of invariant TSC, older CPUs measures different freq for different mul. What to use for real freq measurement here? Some perf.counter?

1. On Sandy/Ivy Bridge it seems it's enough to set Speedstep MSR's on 1 core to get even lower multipliers than set in the BIOS. This changed with Haswell.
2. Yep, Intel uses invariant TSC and unlike on Phenom II there is no known way so far how to reset the TSC after a new working frequency is set.

I see this utility works for a wide range of CPUs, from the K5 to the Athlon 64. I also like that it works in pure DOS and the Windows 98 DOS box. The fine control over speed using cache, multiplier, and throttling is very well designed.

TinPlat wrote on 2026-06-04, 13:36:

I see this utility works for a wide range of CPUs, from the K5 to the Athlon 64. I also like that it works in pure DOS and the Windows 98 DOS box. The fine control over speed using cache, multiplier, and throttling is very well designed.

It works well even beyond Athlon 64. Actually with this utility later Phenom II's become one of the most versatile DOS CPUs.
Phenom II can work from 100 MHz to ~4 GHz under DOS and even the TSC can be reset so it can really report 100 MHz working speed to software.