I have a Pentium 2 Slot 1 and have just installed the second original factory replacement CPU fan which won't spin. The only motherboard power tap is a 2 wire, though the fan has an optional 3 wire plug as well. Is there some setting that needs changing to tell the new fan to spin? If so, where and how do I set it? I'm operating with the case open for now, hoping that the heatsink alone will provide some cooling. Will it? Is there an alternate way to power the fan?

the heat sink alone won't do it. I wouldn't run it without the fan. Try using another one of your power connectors. Maybe the one you are using is bad.

You are really taking a chance running without a fan. If you have a small room fan you could use it temporarily to blow air to the heatsink. Remove the non working fan.

Try using what other power connectors?

There's usually more than one fan power tap. Are you sure you don't have another? Older fans ran from the same power connections as the hard drives. That's what dwin was talking about. You can get an adapter to connect your cpu fan to one of them.

The third wire on your fan cable (usually yellow) is for fan speed sensing which your board obviously does not support. The black wire on the outside connector pin is ground and the red in the middle is supply power. Set the plug over the two motherboard pins to engage these two pin positions. If you have doubts about voltage polarity, you can check it with a meter. The red is +.