Downgrade Monitor or Upgrade CPU?

[CatTNT]

(this is not the PC in my signature)

 

So in the games that i usually play, like Rainbow six Siege and World of tanks (and a few others) are very laggy on my 3440x1440 100HZ monitor. On those 2 games FPS is usually around 70-80, and if something like an explosion happens it will drop down to 40 FPS. The only way to get 100FPS consistently is to put all settings on the lowest possible. So after another posts and some thinking i have narrowed down my options to either upgrading my CPU or downgrading my monitor.

So keep things *affordable* i can either get this https://www.microcenter.com/product/497546/rog-strix-xg32vq-315-wqhd-144hz-hdmi-dp-freesync-curved-gaming-led-monitor

or

https://www.microcenter.com/product/512484/core-i7-9700k-coffee-lake-36-ghz-lga-1151-boxed-processor

 

So what im asking form you guys is if i get the monitor will this be able to play at high settings and no lag?

i5 8400

Strix GTX 1080

Z370 HD3

Samsung 960 Evo

1Gb Ethernet connection

or if i keep my 3440x1440 100HZ monitor. will upgrading the CPU to a 9700k allow me to play at med/high settings with no lag?

What about a 9600K?

 

CPU usage during gaming is around 90% on all cores (task manager)

Later tonight i will check the GPU usage in games

[rev_dude]

If you are spending the same amount of money, I would defiantly upgrade your cpu. Better to take a step forward rather than back  

Beep in mind you will need a cooler to properly overclock though.

[Fasauceome]

7 minutes ago, CatTNT said:

CPU usage during gaming is around 90% on all cores (task manager)

You could probably do with a CPU that has more threads, all of the background tasks are probably gunking up the game. Have you considered an i7 8700?

[XR6]

1 minute ago, rev_dude said:

If you are spending the same amount of money, I would defiantly upgrade your cpu. Better to take a step forward rather than back  

Beep in mind you will need a cooler to properly overclock though.

CPU is definitely the better option. If it's in budget the 8700/8700K is most likely a better option.

 

[CatTNT]

So the monitor is 100$ more, there is  a smaller one that 70$ cheaper than the CPU.  But if i get the CPU it NEEDS to be able to play the games at high settings. Thats all im concerned about

 

or i just wasted 400$ for all intents and purposes has the same problem, not enough performance.

[Fasauceome]

2 minutes ago, CatTNT said:

So the monitor is 100$ more, there is  a smaller one that 70$ cheaper than the CPU.  But if i get the CPU it NEEDS to be able to play the games at high settings. Thats all im concerned about

 

or i just wasted 400$ for all intents and purposes has the same problem, not enough performance.

Downgrading has no purpose when you can impose an fps limit and you usually can. The i7 8700 is a ton better than the 8400 and would obviously reduce CPU usage.

[CatTNT]

1 minute ago, fasauceome said:

Downgrading has no purpose when you can impose an fps limit and you usually can. The i7 8700 is a ton better than the 8400 and would obviously reduce CPU usage.

I tried to limit my refresh rate on my monitor to 60HZ, but that makes it feel even laggier than 80 FPS