For any SS7 (and certain regular Socket 7 motherboards), AMD K6plus CPUs are the best bet with the ability to change the multiplier on the fly thru software from 2.0x to 6.0x (excluding 2.5x). Even better if the motherboard has the option for 50 MHz FSB.

VIA C3 Ezra-T or Nehemiah are Socket 370 CPUs with similar capabilities. Despite being slower than any Intel and AMD CPUs at the same clock frequency, they are more flexible regarding hardware slowdown methods when paired with a suitable motherboard. More info about them here: VIDEO BENCHMARKS (Original title: Settling the VIA C3 performance debate once and for all).

I know it's far too new, but I've seen the 11th gen i7 in my work laptop idle at 498 MHz and boost to 4.8 GHz - now that's range! Haven't tried, but it could probably be locked to 498MHz by modifying the power plan. It would still be too fast for Wing Commander.

If you want something a little older, I have an unlocked P2-300 that'll cover 133-333MHz. As an added bonus, at 133MHz it actually disables the L2, which makes it feel more like a P75. 😜

Kordanor wrote on 2023-06-29, 15:09:

I am wondering if there are any other CPUs, maybe on Slot 1 or others, which have a higher range. Like is there any 1Ghz CPU which you could in theory also run on 150Mhz by just jumpering or changing some BIOS settings?

The AMD FX CPUs can be downclocked to 100MHz and you can also underclock the HT ref. clock to reach 50MHz.

Gmlb256 wrote on 2023-06-29, 15:41:

For any SS7 (and certain regular Socket 7 motherboards), AMD K6plus CPUs are the best bet with the ability to change the multiplier on the fly thru software from 2.0x to 6.0x (excluding 2.5x). Even better if the motherboard has the option for 50 MHz FSB.

VIA C3 Ezra-T or Nehemiah are Socket 370 CPUs with similar capabilities. Despite being slower than any Intel and AMD CPUs at the same clock frequency, they are more flexible regarding hardware slowdown methods when paired with a suitable motherboard. More info about them here: VIDEO BENCHMARKS (Original title: Settling the VIA C3 performance debate once and for all).

Thank you, will have a look at that thread.

Standard Def Steve wrote on 2023-06-29, 15:48:

I know it's far too new, but I've seen the 11th gen i7 in my work laptop idle at 498 MHz and boost to 4.8 GHz - now that's range! Haven't tried, but it could probably be locked to 498MHz by modifying the power plan. It would still be too fast for Wing Commander.

If you want something a little older, I have an unlocked P2-300 that'll cover 133-333MHz. As an added bonus, at 133MHz it actually disables the L2, which makes it feel more like a P75. 😜

Yeah, my question was aimed at retro computing ofc. So the lowest achievable speed should still be in the range of below 200Mhz , and make old games playable with disabling cache for example.
I was mostly wondering because SS7 can handle quite potent graphics cards which it cant really support via the CPU. But if you go faster, can you still also make them as slow as SS7 CPUs can.

I've got a 486 board that can trick a Cyrix 5x86 to go all the way down to 2Mhz.

Totally useless for running anything at that speed.

DrSwizz wrote on 2023-06-29, 16:24:

The AMD FX CPUs can be downclocked to 100MHz and you can also underclock the HT ref. clock to reach 50MHz.

The Phenom II should be able to do the same

Changed the Topic and the initial post a bit to better reflect what I was aiming for.

leileilol wrote on 2023-06-29, 16:52:

DrSwizz wrote on 2023-06-29, 16:24:

The AMD FX CPUs can be downclocked to 100MHz and you can also underclock the HT ref. clock to reach 50MHz.

The Phenom II should be able to do the same

Interesting. I guess you can also disabled cores there?
I suspect that AM2+ will not have any isa slots though and might be problematic to get running native DOS games.

It's more like you have to have support for more than one core, than you need to disable more than one core. So unless you are finding something too fast on a multicore version of NT 3.51 I don't think it's a problem you will run into.

One of these things with a Cyrix MII Lucky Star 5V-1A / 5V-1B review - scaling form XT levels to K6-II levels should go turbo XT to the couple hundred Mhz range where you can get 21st century boards to take over. Need a setmul utility for 1x operation.

Kordanor wrote on 2023-06-29, 15:09:

I am wondering if there are any other CPUs and platforms, maybe Slot 1 or others, which have a higher range. Like is there any 1Ghz CPU which you could in theory also run on 150Mhz by just jumpering or changing some BIOS settings?

On capable slot 1 motherboards, with or without slotket socket 370 adapters, the options can be summarized like this:

• Pentium II Deschutes, semi unlocked retail, multiplier range 2.0x to around 5.5x. But practically ranging 133 to around 400MHz. Reboot required for multiplier change through BIOS or Jumpers.
• Pentium III Coppermine rare engineering sample, unlocked variant, multiplier range 3.0x to around 8.0x. But practically ranging 200 to around 800MHz. Reboot required for multiplier change through BIOS or Jumpers.
• Pentium III Tualatin rare engineering sample, unlocked variant, multiplier range 4.0x to around 14.0x. But practically ranging 266 to around 1400MHz. Reboot required for multiplier change through BIOS or Jumpers.
• VIA C3 Ezra(-T) or Nehemiah socket 370 CPU, multiplier range 3.0x or 4.0x to 16.0x. No reboot required.

IMHO if a system cannot downclock to 200MHz, or preferably 133MHz or lower, then the practical retro-game benefit is little.
Above I assume 66MHz FSB as a minimum. Though a few boards can do 50.
Another thing to note is setting Write combining for the LFB, for VESA videomode performance in DOS.

Kordanor wrote on 2023-06-29, 17:07:

Changed the Topic and the initial post a bit to better reflect what I was aiming for. […]
Show full quote

Changed the Topic and the initial post a bit to better reflect what I was aiming for.

leileilol wrote on 2023-06-29, 16:52:

DrSwizz wrote on 2023-06-29, 16:24:

The AMD FX CPUs can be downclocked to 100MHz and you can also underclock the HT ref. clock to reach 50MHz.

The Phenom II should be able to do the same

Interesting. I guess you can also disabled cores there?
I suspect that AM2+ will not have any isa slots though and might be problematic to get running native DOS games.

The Phenom II only goes down to 800MHz or something like that.

I dug up some CPU-Z validations I did when I first got a FX-8350; the same CPU above 6GHz and below 50MHz:

https://valid.x86.fr/show_oc.php?id=2651801
https://valid.x86.fr/show_oc.php?id=2623245

😀

DrSwizz wrote on 2023-06-29, 19:44:

....
The Phenom II only goes down to 800MHz or something like that.

This is not true. The Phenom II can have a 0.5x multiplier (with the help of dividers):
Re: CpuSpd - A Hardware Based CPU Speed Control Utility for DOS/Win98 Retro Gaming
So assuming a default 200 MHz base clock it can go as low as 100 MHz.