Tetrium wrote:

What board are you using btw? Maybe it's to do with the PCI bus being clocked higher at 75MHz FSB than at 83MHz FSB?
It's hard to tell without knowing your hardware configuration.

It is a PC Chips M571 v3.2A. As noted in the original post, there is a jumper for PCI bus speed ratio, which can be set to 2/5 for 75Mhz (PCI bus at 30Mhz) and 83Mhz (33Mhz) so I'm definitely not overclocking the PCI bus.

I did notice tonight that one of the jumpers used for clock speed doesn't seem to fit very snugly so I might find another jumper and try again... maybe that was the issue when trying 75Mhz bus speed.

RJDog wrote:

I did notice tonight that one of the jumpers used for clock speed doesn't seem to fit very snugly so I might find another jumper and try again... maybe that was the issue when trying 75Mhz bus speed.

It did seem to be the issue.. with the jumper in place, the board boots with the CPU at 3.5 x 75 = 262Mhz. Seems to be quite stable too, unlike when trying to clock it at 3.5 x 83Mhz.

If you're going to overclock a pentium MMX, I'd suggest you use a super 7 board since those are capable of 100Mhz FSB. A couple of months ago I was messing with a 233MHz MMX and got it to 300MHz (3x100 @ 2.95v / Aopen AX59 PRO) perfectly stable. I tried 350Mhz but it was barely stable in DOS, regardless of voltage. Widows would bsod, quake would not launch, duke 3d would freeze. Some people are claiming to have gotten 350Mhz stable at 3.1v

Depends on the sample. There are some mobile P-MMX 266 out there that run on 1.9V by default. As read they go up to 400MHz easy with increased voltage. Will try it when I get my hands on them 😉

kixs wrote:

Depends on the sample. There are some mobile P-MMX 266 out there that run on 1.9V by default. As read they go up to 400MHz easy with increased voltage. Will try it when I get my hands on them 😉

These Tillamooks are kinda extremely limited in their practical use though, even though these are packaged the same way as the PPGA desktop MMX chips.
The main problem is not finding a board in which these will POST and work, but finding a board which doesn't let the Tillamook disable the motherboard cache.

Not really a problem as these will be just for having fun - experimenting. I have around ten SS7 boards. Maybe I get lucky 😉

kixs wrote:

Not really a problem as these will be just for having fun - experimenting. I have around ten SS7 boards. Maybe I get lucky 😉

If you do, feel free to let us know 😁

Is there a list of Tillamook desktop motherboards documented anywhere?

Rhuwyn wrote:

Is there a list of Tillamook desktop motherboards documented anywhere?

Afaik, these chips do work in many boards (provided the supplied voltage is low enough) but I don't know of any board that will actually not have its cache disabled. So the list is either similar to the K6+'s or very very short 🤣