What slows down my computer in-game?

[kilo24]

In Doom 2016 for example, I hover around 60fps when not much is happening but during combat I get stutters and the FPS can often drop into the 20's (medium vs. ultra settings makes no difference). Here's a list of my specs:

OS: Windows 10 Pro 64 Bit
RAM: 16GB
CPU: Intel Core i5-3570K CPU @ 3.4GHz, 4
Cores, 4 Logical Processors
GPU: NVIDIA GeForce GTX 1050 Ti
Motherboard: ASRock Z77 Pro4

What could be the problem? I've verified the GPU is attached to the correct PCI-e slot and that there are no cooling problems. I've tried disabling all startup applications and rebooting, no difference. My RAM is in dual core mode. Perhaps I should also note that sometimes when the computer is performing a heavy task it produces a rattling sound.

 

[kilo24]

Then reaching turbo boost isn't going to get to the bottom of what's wrong with this computer, if it's even being throttled to begin with. Frankly, I've lost faith in your credibility on this issue when all other sources contradict you, you only partially answer my questions and you struggle to even speak English. Goodbye, but at least thank you for probably saving my CPU from damage.