I have swapped my PC's standard 450W power supply with a new 750W and finally got a graphics card for it (GTX 1050 ti). I am not great with the actual physical building of computers and am not familiar with parts or components at all (just switching the power supply was a challenge for me). My problem is that even though my graphics card can run a modern game (I used Rainbow Six Siege for reference) my CPU is still weak and limits me to 15-25 FPS. I would just get a new CPU but my pre-built one has a FM2 slot (not FM2+) and I have found no FM2 slot CPU's that I am interested in. Seeing as though the CPU is the only thing I'm interested in replacing, I was wondering if anyone knew where I could get a pre-build PC with a CPU competent enough to run a modern game (Overwatch/Rainbow 6) at 60+ FPS, but not be incredibly pricey and decked out with things only hardcore enthusiasts would understand/benefit from, then I can swap the power supply and install my graphics card.
(in the picture you can see that the game uses only a little more than half the cards memory, but the FPS in game is still low)