Odd high-pitched chattering on W500 64 bit but on VISTA only

[mgo]

It's a ThinkPad W500 4064A12, running Vista 64 bit on a SSD.

I notice that there is a frequent high-pitched "chattering" at times when the machine is running. The chattering comes and goes. It is less pronounced when running Balanced vs. High Performance power settings. Balanced is quieter. Power Saver is the quietest mode of the three. The sound is similar to head clatter on a mechanical HDD. There is no chattering during boot-up and shutdown, or when running a non-Windows interface.

The chattering sound is also present when running Vista on a mechanical HDD.

My T60 units do not have this "chatter" running XP.

I am assuming this is a ATI Mobility FireGL V5700 characteristic in Vista. I never noticed this in Windows 7 on the same machine. Any ideas or experiences on this annoyance?

(I am running this install on a Intel solid state drive. Yes, I know, Vista isn't too "ssd aware" but I'm giving it a try anyway.)

I've even gone to the "Classic" settings (non-Aero, etc.) and there is no difference. It all seems to be in the video vs. power settings.

thanks!

[mgo]

Answering my own question....found on another forum. Turn off "Speed Step" in BIOS. No performance hit that I notice, and the annoying sound is gone, gone, gone!