Pretty sure that it can go as low as 133 with 2x66, but running x2 multiplier will AFAIK disable L2 cache. But I think that maybe setting multiplier to x5 will actually set x2 with L2 enabled, or that may only be for Klamath core PII?

BetaC wrote on 2022-12-29, 08:48:

As the title says, I'm trying to figure out just how much I can potentially clock down and or slow down my Pentium II system. I'm asking as I have found myself just kind of disillusioned with the 486 and pentium MMX builds that I've been trying to work out as of recent. The 486 wouldn't run the games I wanted it to, and capped out at 503MB. The MMX build has just been a headache thanks to whatever was making it not boot off of anything but a floppy.

This has made me want to return to the seemingly evergreen slot one board that I have. I'm thinking about making a "What I actually want to play" build with it once more, and have a few simple questions. I think 200MHz is the lowest I can go with the PII that I have on my motherboard, which is probably fine for TIE Fighter in 640x480 mode, but I am curious if I could get it to run effectively slower using something like SetMul or something else. Daggerfall is a concern, as it has some strange issues when running a little too fast, as is X-Wing Collector's CD, which is the worst kind of speed sensitive (plays great up until you hit an unintended difficulty spike due to enemies firing their lasers far too fast).

What's the part number and date code of your P2 350?

Tetrium wrote on 2022-12-29, 14:53:

What's the part number and date code of your P2 350?

It ends in 19, and I have already over and underclocked it on my BX board.

BetaC wrote on 2022-12-29, 16:49:

Tetrium wrote on 2022-12-29, 14:53:

What's the part number and date code of your P2 350?

It ends in 19, and I have already over and underclocked it on my BX board.

Yes ok, and the rest is?

Tetrium wrote on 2022-12-29, 18:33:

BetaC wrote on 2022-12-29, 16:49:

Tetrium wrote on 2022-12-29, 14:53:

What's the part number and date code of your P2 350?

It ends in 19, and I have already over and underclocked it on my BX board.

Yes ok, and the rest is?

Had to dig through my old threads, and have free time at work.

BetaC wrote on 2022-12-30, 00:19:

Tetrium wrote on 2022-12-29, 18:33:

BetaC wrote on 2022-12-29, 16:49:

It ends in 19, and I have already over and underclocked it on my BX board.

Yes ok, and the rest is?

1C451A5C-A9DD-44BD-A063-C79584DCA999.jpeg
Had to dig through my old threads, and have free time at work.

Thanks 😀

I've been away for a while. It's the first time I know of a P2 350 that is not fully locked.

100 Mhz without working L2 cache on specific motherboards. Possibly could be lower with direct PLL tinkering (hardware modding).

The Serpent Rider wrote on 2022-12-30, 09:47:

100 Mhz without working L2 cache on specific motherboards. Possibly could be lower with direct PLL tinkering (hardware modding).

Yeah, I can only go down to 3.5x66 unless the processor interprets something above that as below it.

BetaC wrote on 2022-12-30, 20:39:

The Serpent Rider wrote on 2022-12-30, 09:47:

100 Mhz without working L2 cache on specific motherboards. Possibly could be lower with direct PLL tinkering (hardware modding).

Yeah, I can only go down to 3.5x66 unless the processor interprets something above that as below it.

You mean that your CPU doesn't recognize any multipliers below 3.5? That's odd. Usually with a non-locked slot 1 CPU the lower multipliers are not locked. Unless this CPU is not multiplier unlocked, but then what was H3nrik V! talking about?

Just a general comment to clarify a few things, just in case. If one wants to know how far one can underclock a slot 1 CPU, one of the first things you'd need to find out is whether or not your slot 1 CPU has a locked multiplier.

The earlier slot 1 CPUs usually did have an unlocked multiplier or at least partially in that they had a maximum CPU multiplier (with everything below that unlocked), somewhat similar to the P1 MMX CPUs.
Later ones are more often multiplier locked (and I mean fully locked).

Tetrium wrote on 2022-12-30, 23:36:

BetaC wrote on 2022-12-30, 20:39:

The Serpent Rider wrote on 2022-12-30, 09:47:

100 Mhz without working L2 cache on specific motherboards. Possibly could be lower with direct PLL tinkering (hardware modding).

Yeah, I can only go down to 3.5x66 unless the processor interprets something above that as below it.

You mean that your CPU doesn't recognize any multipliers below 3.5? That's odd. Usually with a non-locked slot 1 CPU the lower multipliers are not locked. Unless this CPU is not multiplier unlocked, but then what was H3nrik V! talking about?

Sorry for the confusion. 3.5 is the lowest my motherboard supports

BetaC wrote on 2022-12-31, 00:55:

Sorry for the confusion. 3.5 is the lowest my motherboard supports

Perhaps 3.5 is lowest that is documented?
I think the first Deschutes Pentium II like your 350 have unlocked multi because Intel wanted them to run in Klamath mainboards with FSB 66 MHz and a 5x multi (you may need microcode updates to that BIOS then).
Your Pentium II 350 is the slowest with Deschutes core, so you may try up to 400 or 450 MHz. Perhaps you'll get happy with 400 MHz, but the L2 cache may fail first.

BetaC wrote on 2022-12-31, 00:55:

Tetrium wrote on 2022-12-30, 23:36:

BetaC wrote on 2022-12-30, 20:39:

Yeah, I can only go down to 3.5x66 unless the processor interprets something above that as below it.

You mean that your CPU doesn't recognize any multipliers below 3.5? That's odd. Usually with a non-locked slot 1 CPU the lower multipliers are not locked. Unless this CPU is not multiplier unlocked, but then what was H3nrik V! talking about?

Sorry for the confusion. 3.5 is the lowest my motherboard supports

Yes, this is why it's a good idea to state the parts used in the OP because being vague often creates more confusion.

What motherboard are you using?
Unless your board is some kind of (usually non-standard) OEM board (or perhaps one of those uncommon jumperless ones?), your board should have a jumper block which most likely is able to be set below 3.5x CPU multiplier. If not, it should be able to set the CPU multiplier in the BIOS.

tldr, your board should be able to set the CPU multiplier below 3.5

EDIT: If you can't set the CPU multiplier below 3.5x, can you confirm you can set the CPU multiplier to 4.0 or higher? Because if your current system can't do that either, then I'd assume that particular CPU is fully locked.

Disruptor wrote on 2022-12-31, 01:18:

BetaC wrote on 2022-12-31, 00:55:

Sorry for the confusion. 3.5 is the lowest my motherboard supports

Perhaps 3.5 is lowest that is documented?

I guess this is possible, though to me it seems unlikely.

I think the first Deschutes Pentium II like your 350 have unlocked multi because Intel wanted them to run in Klamath mainboards with FSB 66 MHz and a 5x multi (you may need microcode updates to that BIOS then).
Your Pentium II 350 is the slowest with Deschutes core, so you may try up to 400 or 450 MHz. Perhaps you'll get happy with 400 MHz, but the L2 cache may fail first.

The slowest Slot 1 Deschutes runs at 266MHz.

I have 2 x P2 350 MHz, and both run perfectly fine at 466 MHz (133MHz x 3.5), and they are quite fast due to the fast FSB frequency.
Sadly, mine have a factory locked multiplier, so, on specific motherboards, the slowest possible achievable speed is 175 MHz (50MHz x 3.5).

Anyway, even with an unlocked multiplier, slowdown options (that are actually usable) with a P2 will remain limited.
If you're looking for the ultimate flexible 440BX build, then the VIA C3 Ezra-T is what you want: not only is it faster than any P2, but it can also be slowed down to virtually ANY speed you want (slow 386, fast 386, slow 486, fast 486, slow Pentium, fast Pentium, and anything in between).

Tetrium wrote on 2022-12-31, 11:36:

The slowest Slot 1 Deschutes runs at 266MHz.

Sorry. You're right. I meant the slowest FSB100 Deschutes.

Tetrium wrote on 2022-12-31, 11:27:

Yes, this is why it's a good idea to state the parts used in the OP because being vague often creates more confusion. […]
Show full quote

BetaC wrote on 2022-12-31, 00:55:

Tetrium wrote on 2022-12-30, 23:36:

You mean that your CPU doesn't recognize any multipliers below 3.5? That's odd. Usually with a non-locked slot 1 CPU the lower multipliers are not locked. Unless this CPU is not multiplier unlocked, but then what was H3nrik V! talking about?

Sorry for the confusion. 3.5 is the lowest my motherboard supports

Yes, this is why it's a good idea to state the parts used in the OP because being vague often creates more confusion.

What motherboard are you using?
Unless your board is some kind of (usually non-standard) OEM board (or perhaps one of those uncommon jumperless ones?), your board should have a jumper block which most likely is able to be set below 3.5x CPU multiplier. If not, it should be able to set the CPU multiplier in the BIOS.

tldr, your board should be able to set the CPU multiplier below 3.5

EDIT: If you can't set the CPU multiplier below 3.5x, can you confirm you can set the CPU multiplier to 4.0 or higher? Because if your current system can't do that either, then I'd assume that particular CPU is fully locked.

To be honest I wasn’t fully expecting a hardware based answer. I was kind of expecting a general answer 🤣. I’m using the same Gigabyte GA-6BXC V2. It’s good for most things, supporting multiple points between 66 and 133 while having three ISA slots. I don’t know if it’s Tualatin compatible but it rocks a coppermine.

BetaC wrote on 2022-12-31, 18:07:

To be honest I wasn’t fully expecting a hardware based answer. I was kind of expecting a general answer 🤣. I’m using the same Gigabyte GA-6BXC V2. It’s good for most things, supporting multiple points between 66 and 133 while having three ISA slots. I don’t know if it’s Tualatin compatible but it rocks a coppermine.

The GA-6BXC is even better than you think. Not only does it support FSB frequencies between 50 and 133 MHz, but you can use SoftFSB to control the FSB frequency from within DOS and Win98.
It's actually the ideal pair for a VIA C3 Ezra-T 😁

BetaC wrote on 2022-12-31, 18:07:

Tetrium wrote on 2022-12-31, 11:27:

Yes, this is why it's a good idea to state the parts used in the OP because being vague often creates more confusion. […]
Show full quote

BetaC wrote on 2022-12-31, 00:55:

Sorry for the confusion. 3.5 is the lowest my motherboard supports

Yes, this is why it's a good idea to state the parts used in the OP because being vague often creates more confusion.

What motherboard are you using?
Unless your board is some kind of (usually non-standard) OEM board (or perhaps one of those uncommon jumperless ones?), your board should have a jumper block which most likely is able to be set below 3.5x CPU multiplier. If not, it should be able to set the CPU multiplier in the BIOS.

tldr, your board should be able to set the CPU multiplier below 3.5

EDIT: If you can't set the CPU multiplier below 3.5x, can you confirm you can set the CPU multiplier to 4.0 or higher? Because if your current system can't do that either, then I'd assume that particular CPU is fully locked.

To be honest I wasn’t fully expecting a hardware based answer. I was kind of expecting a general answer 🤣. I’m using the same Gigabyte GA-6BXC V2. It’s good for most things, supporting multiple points between 66 and 133 while having three ISA slots. I don’t know if it’s Tualatin compatible but it rocks a coppermine.

A general answer to

How much can I get out of an unlocked PII 350?

you say?

Well, I'd say the general answer to this question is

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it depends.

😜