Question My Computer is Underperforming!

[ComputersAreHard]

My Specs:
i5 9600K 1151 LGA - NEW
DDR4 16GB G.Skill Dual Channel - NEW
ROG STRIX Z390-E GAMING Motherboard - NEW
Nvidia Strix GTX970 Graphics Card - OLD
SSD Samsung - OLD
1TB Western Digital Harddrive - OLD

My heatsink is a intel heatsink old one from another computer and isnt pinned down properly, so Im assuming the heat from the cpu is making my fps drop and my computer underperform!
Also, I recently got a new Rival 3 Steelseries mouse that will time to time stand still for a solid second and then move where im moving the mouse too [Mouse feels floaty kinda moves side by side weirdly]

 

[CountMike]

My Specs:
i5 9600K 1151 LGA - NEW
DDR4 16GB G.Skill Dual Channel - NEW
ROG STRIX Z390-E GAMING Motherboard - NEW
Nvidia Strix GTX970 Graphics Card - OLD
SSD Samsung - OLD
1TB Western Digital Harddrive - OLD

My heatsink is a intel heatsink old one from another computer and isnt pinned down properly, so Im assuming the heat from the cpu is making my fps drop and my computer underperform!
Also, I recently got a new Rival 3 Steelseries mouse that will time to time stand still for a solid second and then move where im moving the mouse too [Mouse feels floaty kinda moves side by side weirdly]

Well, any CPU will throttle down when overheated, you should fix that first.