Holding in Reset Button

I was messing with my computer today, and I tried holding in the reset button to see what it would do. What I found out is, if you hold it in, the computer seems not to do anything but make a noise like an engine revving repeatedly. (Hard drive?)
So, what exactly is happening when I do this, and is it a really bad idea to wire a toggle switch in to close that circuit in place of the reset button?

Depends on the computer, i’d bet. But the ones i’ve done it on seem to be basically held at the first state of the boot procedure or being constantly restarted really, really quickly.

I think the engine revving noise would probably be a fan constantly being pulsed on and off really quickly.

I see. It’s an Intel DQ965GF motherboard, if it helps.