I really need some help here with my PC here

So i got a new Graphics Card for Christmas right, I've been playing games like Metal Gear Phantom Pain all on high settings smooth 60fps.
One day i turned on my PC and now it's really done itself one, unstable fps with huge drops every few seconds, even with everything set to low. It's cancer.

This happens with even the low end games, every single one of em'

I don't know what's happend and it's really been frying my head, i can't find why this has happend.

PC Specs:

>Processor AMD A8-7650K Radeon R7, 10 Compute Cores 4C+6G
>Video Card Radeon(TM) RX 460 Graphics
>RAM 8.0 GB
>Operating System Microsoft Windows 10 (build 14393), 64-bit