gerwin wrote:An unlocked intel PII/III still does not support changing the Multiplier with software, except for mobiles with speedstep, as already mentioned. But speedstep in that generation does not mean that the multipliers you want will be available. For example: the Mobile Pentium III 600 with speedstep only goes down to 500MHz.
(I actually have this particular chip soldered on a rare socket 370 adapter PCB. But it was dead on arrival.)
Have you considered a VIA C3 Nehemiah processor? It is not as fast per clock as an intel Pentium but it does have the features you desire.
Just been looking into that... The only, non-mobile, unlocked PII/III processors that could be found are special tech releases and extremely rare. No way I could afford one on the extremely unlikely event it became available. Not saying that public release, non-mobile, PII/III chips definitely do not exist, but I coulddn't find any.
As for the mobile processors, the multiplier adjustment range varies from chip to chip. I've seen them go as low as 2x, while others wouldn't go below 7 or 8. This, along with not remembering a limitation of my current MB correctly, ends the tentative plans I had made. As it stands now, I can chose between 700 Mhz, 933 Mhz, & 1400 Mhz (without overclocking.) At best, with a CPU that can go down to 2x (the VIA C3 only goes down to 5x,) I could go down to 100 Mhz. With the C3 I could go down to 250 Mhz.
My Voodoo system was primarily designed around a set of Voodoo cards I had. It was also meant to run some of my favorite 3dfx games. Some of them, back when they were new, chugged rather sluggishly on a 600 Mhz system I had then, which is why I went for the 1.4 Ghz I have now. Note: They run just great 😀 I also wanted it to be able to go back as far as possible into the DOS era as well. So, it does what I originally wanted it to, I was just looking at options to extend this, if any.
All that being said. Switching to the VIA C3 might actually be an option. If it will actually run at 50 Mhz FSB. Between dropping the FSB to 50 Mhz, the Multiplier to 5x, and disabling the cache (any/all,) I should be able to get old DOS compatibility to be rather extensive. The only issue there is, for the 100Mhz FSB (the fastest my MB can handle without overclocking,) the C3 only goes up to 900 Mhz. There is a C3 1.4 Ghz chip, but it uses 133Mhz FSB with 10.5x Multiplier. I honestly don't know the effects on a chip if the FSB & multiplier are changed but result in the same final speed (switching 133 x 10.5 to 100 x 14 for example.) That would require running the multiplier change on every boot as well (changing it from the HW 10.5 to SW 14.)
