Those look Torx-y.

That's just the scew head and has nothing to do with the shaft diameter or thread pitch.

Well it looks like M3

It's definitely not M3. It might actually be M3.5. I just took a set of calipers to my bag labeled M3.5 and they measured 3mm.

A001 wrote on 2024-09-03, 21:16:

Well it looks like M3

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What is length of that shaft?

Kahenraz wrote on 2024-09-03, 19:27:

I didn't think to measure these before discarding them and they don't match anything that I have on-hand. […]
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I didn't think to measure these before discarding them and they don't match anything that I have on-hand.

I have found M3 and M3.5 to be too small, M4 to be too large, and #6-32 to be the wrong thread or slightly too large.

Does anyone know what these screw threads are?

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The ones I have replaced I use 6-32 and they thread in just fine.

Those wire cutter/stripper/crimper tools come in metric and imperial and you can use the screw cutter holes as thread gauges since they are labelled and threaded.

Pentium 2 SECC heat sink removal

Pentium 2/3 slot 1 CPU retention mechanism screw size/pitch

It seems that it's a bit of a mystery, especially since they are like screw/rivet hybrids ...

There is also this Intel branded heatsink with similar screws.

Kahenraz wrote on 2022-03-24, 12:06:

It's a hex head for an allen key; a tapered one is best for corroded holes, so that it can grip firmly, even after deteriorating […]
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appiah4 wrote on 2022-03-24, 10:24:

I am trying to remove the HSF from a PII-350 I own so that I can mount it on a PII-400 I recently purchased. However, there is a problem: I can't seem to figure out how to remove this bolts/screws that have it tied down. Are these small allen key screws? Are they torx screws? Anyone have experience with removing and remounting these?

It's a hex head for an allen key; a tapered one is best for corroded holes, so that it can grip firmly, even after deteriorating. Ideally you'll want to apply vinegar to dissolve the corrosion and then some oil to loosen the screw. Be liberal with the oil or you risk stripping the screw. If it becomes stripped then you will have to drill it out.

Re: I recently found this hardware, AKA the Dumpster find thread.

Kahenraz wrote on 2021-09-06, 15:48:

I bought a slot 1 CPU with an Intel branded heatsink and cooler. I wondered why the fan wasn't spinning up so I opened it up to investigate. The entire fan assembly is destroyed by corrosion.

What's worse is that the screws that hold it to the processor housing were completely rusted and two of the four screws stripped immediately while trying to remove them.

Kahenraz wrote on 2021-09-07, 09:16:

I managed to get the heatsink off by pouring some oil around the screws and using a high quality steel torx bit that had a bit of a taper that allowed it to bite.

The next difficulty then was disassembling the processor housing as it needed a proper cleaning after having oil dripped into it. This is not an easy thing to do as the housing is pressure-fit and not designed to come apart. Later Pentium 3s are a lot better in that they are very easy to disassemble.

A001 wrote on 2024-09-03, 21:16:

Well it looks like M3

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They actually use self tapping screws (aluminum), you can tell by the way the threads that engaged the metal are smashed down.

As you can see from the intel specs the holes are called out with a tolerance and a thread isnt specified. The holes are specced at .124 Dia. and thats perfect size for 6-32 form thread at 65%. If you have a good quality machine screw (Steel) it can easily form threads in the thin alum plate. 3.5 mm could also be used but that would be an 75%+ thread that take much more force to form.

They mention tapping screws in this as well:

Not sure how I missed these.

What the heck is Rivscrew? Is there any comparable size and thread? I guess that's why everyone comments that the screw looks like a rivet.

Kahenraz wrote on 2024-09-05, 01:19:

What the heck is Rivscrew? Is there any comparable size and thread? I guess that's why everyone comments that the screw looks like a rivet.

They look like drive screws to me. One time screws that are pressed/tapped in

That's unfortunate... So there aren't any true threads on these at all. I am extremely hesitant to self-tap screws into one of these. I feel like little micro particles of metal falling into the CPU cartridges is a recipe for disaster.

Kahenraz wrote on 2024-09-05, 01:19:

What the heck is Rivscrew? Is there any comparable size and thread? I guess that's why everyone comments that the screw looks like a rivet.

This has come up on the forum previously - they were developed by a UK company called Avdel (now part of STANLEY Fastenings)...the actual part no. will depend on the heatsink specs relative to Intels own default thermal solution specs for the processor.

If you're lazy like me, find some longer, narrower bolts with nuts.
Done.

myne wrote on 2024-09-05, 04:29:

If you're lazy like me, find some longer, narrower bolts with nuts.
Done.

I can only see this working by fastening the heatsink to the heat spreader first while the cartridge is disassembled and then putting it back together. Otherwise, how would you get the nut or head of the bolt on the inside of the sealed cartridge?

myne wrote on 2024-09-05, 04:29:

If you're lazy like me, find some longer, narrower bolts with nuts.
Done.

I think I recall doing it with the small gauge nuts and bolts you used to be able to find at the back of RadioShack.... so yah, that was a while ago.

Kahenraz wrote on 2024-09-05, 04:34:

myne wrote on 2024-09-05, 04:29:

If you're lazy like me, find some longer, narrower bolts with nuts.
Done.

I can only see this working by fastening the heatsink to the heat spreader first while the cartridge is disassembled and then putting it back together. Otherwise, how would you get the nut or head of the bolt on the inside of the sealed cartridge?

Dont the screw holes go all the way through?
Bolts narrow enough to fit through those holes.