Well I've made a few threads about experiencing lag spikes when gaming. This is a pre built low end gaming PC made by PC Specialist. It comes with a i3 4170, 1x8GB 1600 RAM, 1TB HDD and GT 740 2gb. I upgraded to a 9602GB, everything still went good. Then when I upgraded to a i7 4790 which was 2nd hand, my PC all of a sudden couldn't handle high end games such ass PUGB, GTA5 and DayZ. I've Reformatted my PC, updated BIOS cleaning dust from my rig and so much. But soon as I put my old CPU back in, everything runs smoother. So why would this happen? Here are my prev topics: