Monitor not power saving correctly after XP install.

Hi,

After installing XP, my monitor's power saving mode is not quite right.
After leaving the computer for a while, the power light goes amber which
is "stand by" mode (50 watts). When I had Windows 98 it the amber light
would flash which was "Power off mode" (less than 8 watts).

I double checked by booting up in Windows 98 and it still works (so I've
not changed the BIOS and forgotten or something like that).

The monitor (Samsung SyncMaster 500s+) only goes in to "power off mode"
if the horizontal and vertical sync are off. As it's only going into
standby mode, the vertical sync must still be on.

So whatever part of the OS or video card or driver or whatever that
turned off vertical sync is no longer working. Something is working
though as the horizontal sync is going off and the screen is blanking -
I do have the basic power save feature of Windows enabled.

The video card is a Nvida GEforce 440MX. I installed the latest drivers
(which I didn't do on 98 so perhaps that's a clue). The various Windows
property pages identify the card and the monitor correctly.

Any ideas?

Cheers

Peter