Ive just built my new pc and installed windows 8.1 on it.
however whenever I come to sleep it, I can choose the sleep option, but all it does is act like its going into sleep mode (PC screen goes black) then it just turns itself back on?
There are no USB's plugged in except my wireless keyboard and mouse.
Is it possibly a driver problem? or a program stopping it from sleeping?
Any suggestions would be brilliant
Typically it's because it's waking from the network adapter. You can go to device manager, right click it and under power management uncheck an option that says "allow this device to wake the computer."
You can check what other devices can wake it by opening an elevated cmd prompt and type:
powercfg -devicequery wake_armed