Screen goes black while gaming and sleeps while AFK!

[iMandoz]

Hello there the last couple of days my screen shuts off on its own when I'm afk even though I set my windows setting to never sleep and I don't have a screen saver, when I move my mouse it starts normally but I don't know why it does that even though the settings is never.
I don't really know if this is related to the problem but as I started to play The Witcher 3, after about 10 mins of playing my screen went black even though the monitor stayed on!, I had to shut it off then on so it would work again.

Here are my specs:

Windows 7 Ultimate 64bit
Core i5-2500k 3.30 Ghz
4 GB RAM
Geforce GTX 560
P61-USB3-B3 Motherboard

I have checked if its an over heat problem but it's not, all my temps are about 40C, I have checked my cables and updated all my drivers, I have checked many threads who seem to have the same problem as me but none of the solutions worked for me nor they have the exact same problem. I don't really have the option to try my graphics card or monitor with another computer, sorry for the long thread.
Thanks in advance.

 

[wei_wei]

what kind of black screen you have?is it like black screen but PC still running or like power cut off?
how old is your PSU?

 

[iMandoz]

what kind of black screen you have?is it like black screen but PC still running or like power cut off?
how old is your PSU?

The monitor is on and the pc is on but the screen is black. That's when I'm gaming, but when I leave the computer the monitor shuts off and the button light flashes on and off like its in sleep mode. My PSU is about 2 years old.

 

[wei_wei]

try clean your GPU golden finger and reseat your GPU again