Computer won't sleep

Solution 1:

do you say that you have a motherboard that support usb 3.0 well that a well know issue that happened when the box is in suspend mode,

When the XHCI module is loaded for USB 3.0 operation the system cannot suspend. Manually unloading XHCI will allow suspend to complete normally. To avoid future suspend problems, the workaround is to add SUSPEND_MODULES="xhci-hcd" to /etc/pm/config.d/unload_module then the system can suspend normally.

P7P55D-E

* Intel LGA1156 Platform / Intel® P55 Express Chipset
* **True USB 3.0** or SATA 6Gb/s Support - Future Transfer Technology
* ASUS Hybrid Technology
* ASUS 16 Hybrid Phase Design*
  *16 Hybrid Phase = 12+2 Phase x T.Probe
* TurboV EVO - Ultimate O.C. Processor
* T.Probe - Leading Active Cooling Technology 

Description of the bug and How to Fix : here