if it's this, it's a 430HX chipset. even though the article claims that an MMX upgrade is possible, i don't see any circuitry for that and the VRM spot isn't populated either. check if your board has anything in that spot, otherwise you'd probably have to get one of those rare overdrives.

as for the CF card, that's quite an expensive adapter for something that didn't wind up working, maybe return it, get some working old HDD and call it a day? otherwise, new CF cards should still be readily available.

Thanks for the reply ... Yes, that's the same model I have. (IBM PC 350, 6587-90U)

I think that article is referring to the Wikipedia article about the IBM PCs. It mentions these models coming with "up to" a Pentium 233 MMX.

What spot on the motherboard are you referring to for the VRM?

I have a Pentium 233 MMX I was going to plug in soon but I don't want to fry it or the motherboard of course...

EDIT: I actually posted this question a few days ago over here: Does this IBM PC 350 support Pentium MMX 233? (re: 200 MHz maximum speed?)

those two rows of solder points here, where "VRM" is silkscreened: https://ancientelectronics.files.wordpress.co … 8.jpg?w=2000&h=

well pentium mmx requires ~2.8V while the regular pentiums were ~3.3V or often even ~3.5V for the pentium 166/200, so it's for the best you didn't just plug it in.

as for the fan question, the case fan should be sufficient with that heatsink.

Here is my motherboard:

It looks like the one in the picture but I don't see any empty VRM pads?

This post seems to suggest it supports it: My IBM PC 330

...but I don't know the revision of the motherboard he was using.

well those solder points are for the VRM module connector that some boards would have.

maybe just use the thing as-is instead of already worrying about upgrades? pentium 166 to pentium 233 mmx wasn't quite an earth-shattering upgrade IMO.