Question FPS drops and noisy fans, how to find the bottleneck?

[TenaciousD]

When i build my pc in 2017 i was able to run The Witcher 3 on high/ultra. Recently the fans started to make noise when gaming (i do regularly clean the dust), and I experience significant fps drops. I can not play any AAA games anymore, only low graphics indie games. How can I find out which piece of hardware to replace? I don't wanna buy an expensive new graphics card, and then find out that the CPU was causing the problem.

This is my setup:
CPU: Intel Core i5-7600K
GPU: Nvidia GTX 1070
SSD: Samsung 850 Evo 250GB
HDD: WD Blue 3TB (2015) -
RAM: HyperX Fury DDR4 2133 C14 1x8GB -
MBD: Asus PRIME Z270-P

 

[sizzling]

What are the cpu and gpu temperatures when gaming? Are you gaming at 1080p? What cpu cooler do you have?

 

[McDulle]

A easy program to try is moo0 system monitor.
found @: https://www.moo0.com/
It estimates the current bottleneck while using your pc, gives temps ect...

 

[TenaciousD]

With the Unigine Benchmark on extreme settings my GPU temperature reached a max of 73C.
I game at 1080p.
I use the Cooler Master GeminII M4

 

[sizzling]

With the Unigine Benchmark on extreme settings my GPU temperature reached a max of 73C.
I game at 1080p.
I use the Cooler Master GeminII M4

And cpu temperature?

 

[TenaciousD]

I used NZXT CAM to monitor my pc during a Unigine Benchmark on extreme settings, with the following results:
CPU
load: 36%
temp: 36C
Clock: 4107 MHz
Fan: 701 RMP

GPU
load: 98%
temp: 70C
Clock: 1898 MHz
Fan: 1670 RMP

RAM
load: 90%