Question horrible perfomance issues while gaming.

Dec 14, 2020
I recently got this used cpu, the motherboard Is an ASUS TUF Z370-PLUS GAMING, I7 8700 processor.... when I first built It I had to use a WD Blue 2.5 320gb (HDD) from my 8 years old laptop, the disk Is In good conditions (I suppose) however Its pretty old and doesn't have that much space. Im not sure how many times this cpu has but the seller told me Its on perfect conditions. Afterwards, I bought a gygabite rx 580 (8gb ram) and since I Installed I have been having horrible perfomance issues at games. I dont know much about pcs but Ive looking for an answer and still cant find It. I dont know If Its the cpu that Is causing all this problems, or the gpu or anything else Im just extremely tired of trying everything. I downloaded intel extreme tuning utility and I have these results down here: processor cache freq variates from 3.31hz to 3.71hz sometimes 4hz but Im not even sure, heres an example of my fps drops In almost all games

as you can see the clock In both gpu and cpu dips at the exact moment of the drop, that happens In almost all my games...
I dont now If my pc Is broken I really dont know anything but Its just annoying this Is happening.

heres my last benchmark :

I really hope your help