Windows 7 goes to Sleep but cannot be put to Sleep

[PaulW]

I have quadcore Win7 machine. At one time I could put the computer to sleep by using the start button and moving to the options and clicking Sleep. I have the hibernate button and and the sleep button. My power settings call for sleep after 20 minutes and that works as expected. When I press the sleep button the machine starts to go to sleep by turning off the monitor (NVidia GForce), turns off the power light on the front panel, but I still hear fans running. I have a heat(?) problem which causes the system to crash and restart periodically therefore I would like to put it to sleep when I will be away from the machine for a while. I am not sure where to start my trouble shooting, does anyone have any suggestions?

TIA

[DaveA]

You need to solve the heat problem, and then worry about the sleep issue.

[PaulW]

Hi Dave,
Thanks for the response. I've had the heat problem almost from the beginning. My Nvidia GeForce 8800GTS (PCI Express) runs at about 58 to 61 deg celcius all the time. I have 5 fans, but still occasionally it crashes.

Went to power setting and did a revert to original. Lost the hibernate button, but can now put it to sleep!