Ok, it turned out to be a Compaq thermal sensor that would tell the case fan to ramp up the speed if temperatures rise. If not connected on those mobos the board would give a warning on boot, requiring a keystroke to continue. On other boards, this can simply be ignored. It's not connected to the CPU in any way.

Thanks to Eric for information.

I would recommend replacing it with an active cooler.

tegrady wrote:

I would recommend replacing it with an active cooler.

Is that really necessary? Even under DOS where there is no throttling going on whatsoever it doesnt run that hot even after an hour of sitting on the command line. It never reaches too hot to touch states, so is an active cooler really necessary ?

I saw one of those in a big compaq server once. There was a big fan at the back of the server case and a plastic air duct from the back fan leading to the cpu, so I think it needs pretty good air flow if you don't have a fan on the heatsink itself.

Cool parts = happy, long life parts.

Even in cases where it's not strictly necessary, airflow across a heatsink is generally a good idea.

If you have some air flow going through the case the active cooler isn't needed. Try to undervolt it a bit if your mobo allows manual voltage selection ! -0.1V would help a bit with the heat

It's an HP Vectra VE.
Those Desktop cases have air taken in through the 90W PSU, so that air stays rather cool and gets redirected directily past the passive heat sink fins of the Slot 1. This should do the deal.

Slot 1 passive heatsinks always had a fan real close to the CPU
If it is hot to touch just rig a fan to increase airflow over the heatsink and you should be more then alright.

I once bought a server desktop case with a temperature activated fan - that fan would go on and off every several seconds and drove me nuts. If this is what you have, might want to change the fan and/or where it is connected.

My dual PII 400 workstation came with only a rear case fan near to the CPU heatsinks.