Egilbe , the thing is I added the parts and the wierd thing is that when I'm running some games it will cause it to crash and reboot, some examples of crashes are: Mortal: Online , Left 4 Dead 2 and Bioshock Infinite .
But games like The Binding of Isaac , Dark Souls and some other games I don't experience this problem.
To answer your question , I was told by the person that took look at my pc to try to run some games without the old RAM I had (2x 2 GB RAM) and with the one I bought (1x 4 GB RAM) and vice versa. I am currently testing with the 4 GB RAM and experienced a reboot while playing Mortal: Online, however when I removed the old 2x 2GB RAM I played that same game for around 1h - 1h and 30min and experienced no reboots.
System Specs:
(Before)
Graphics Card - Asus HD 5770 1 GB DDR3 (I don't have my old graphics card with me now and don't remenber it fully but I try my best)
RAM - 2x 2 GB RAM DDR3 (Can't remenber)
CPU - Intel Core i5 750 @ 2.67 GHz
Motherboard - Asus Motherboard P7P55D-E
PSU - NOX Urano II 630 W
(After)
Graphics Card - NVIDIA GeoForce GTX 660 Ti
RAM - Corsair Vengeance 4 GB
CPU - Intel Core i5 750 @ 2.67 GHz
Motherboard - Asus Motherboard P7P55D-E
PSU - NOX Urano II 630 W
(Don't know if I got everything).