Vista - Motherboard fans won't turn off in sleep mode anymore.

I have an HP media center PC running x64 Vista, when I usually put the PC in sleep mode (I'm assuming s3?) the case fans, PS fans and CPU fan would all cut off, now they do not. I have been reading and scanning forums all day on the subject and find no fixes. The closest thing I can come to is a registry setting? There are no power management options in BIOS(the BIOS is the most recent release, I checked).

Any suggestions appreciated!
JC Carmichael

Fans won't cut off as in woon't turn off or keep on going? Have you tried flashing the BIOS?

I had the same problem recently with my PC, it seemed very temperamental, go to control panel/power options. I think how it helped me was turning off every setting under the sun when the computer was given the command to go to sleep. so HDD's off, everything.
My bios has advanced features of these settings too, but often OEM bios's such as HP, Dell etc often dont, so its all OS based on this.

When you say flash the BIOS you mean just reinstall the existing one? And when I say won't cut off, I mean that the fans are only off when I actually fully SHUT DOWN the PC. It's quite annoying. It's only behaved like this for a couple of days. I've had this machine for over a year now, with no hiccups :P

As for the power settings from the OS, I just tried turning everything to always on, with no result from the fans.

Look for the newest BIOS available. Type msinfo32 into the start menu and press enter. Look for your BIOS type in the overview panel. You can also check in dxdiag.

so what exactly do you do to get you pc to go to "sleep".
start/power/sleep?
go to the power options again. If you press a key on your keyboard your pc "wakes up" when it is asleep correct?
Try in power options/change plan settings and click advanced, switch of the Hard drives when you put your pc to sleep, everything!