I understand that you are having problems resuming from sleep mode.
From the motherboard side I can recommend you to update the BIOS and load the BIOS defaults. Remove any non essential component as these may prevent the sleep states to work properly.
Please note that the sleep requires that every device connected supports them. A power supply, video card, hard drive, etc not working properly can cause this behavior.
You're not referring to the computers non ability to wake from sleep are you? There are other discussions on this board where after a recent BIOS upate and attempting to wake the computer from sleep the computer goes into a cycle where it keeps trying to power up but cant.
thank you for you rapid answer.
In the meantime,i found that the H.D led was disconnected and fixed it.
Now the wake up from sleep is OK
Can you explain it ?