You don't really need a fan on top of the heatsink for that CPU, any 80mm case fan blowing some air nearby will be enough. DX4 CPU runs quite cool and normally just a heatsink should be fine, but the overdrive has a voltage regulator that adds quite a bit of heat to the mix which is why a fan is suggested.

Not sure about the fan header as I'm not familiar with IBM boards, but it probably delivers 12V (or 5V), you should probe it with a multimeter and see what you get. I assume it's a standard jumper header, in that case any 2.54mm pitch connector like Dupont should fit well.

It doesn't run cool but a weak fan will work. I bought an ODPR-100 with heat damage not too long ago. 3dBench runs but with mixed up polygons, most programs fail to load. But at 75Mhz it runs perfect.

I bought a second ODP-100 and put a 40mm fan on it.

Need to make a custom connection to what you want to plug it into

I use a 40mm Noctua fan. I attached it sideways to the heatsink using zip ties. It looks a little weird, but it works.

Shponglefan wrote on 2025-03-21, 14:54:

I use a 40mm Noctua fan. I attached it sideways to the heatsink using zip ties. It looks a little weird, but it works.

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This looks pretty decent to me.

I am looking at this 40mm one but the question is how do I make it stick to the CPU heatsink? So far the only solution I see is Shponglefan's zipties.

Another option would be to remove the heatsink of the DX4ODPR100 and put that instead. Or perhaps it would be simpler to just by a DX4 without heatsink and glue the new heatsink with fan on top of it.

If you use a 40x10mm fan, you can secure it with two long screws through the standard heatsink