What kinds of games do you play?
How do you assess performance?
Many fast action games will be limited by the graphics card.
What model of the samsung 49" monitor did you buy?
One has 3840 x 1080 resolution, and another has 5120 x 1440.
The latter will be much more demanding on your graphics card for fast action gaming.
Likely, you will want to upgrade your GTX980ti.
Tom's gpu hierarchy chart gives you a good idea of what you can get.
https://www.tomshardware.com/reviews/gpu-hierarchy,4388.html
For fast action, a 3070 class card or better is in order for the high res version.
I might be inclined to go slow and see how you do with your 980ti.
You will want a stronger/better psu.
850w will do, but 1000w usually costs little more.
That lets you up the graphics card in the future.
A psu will only draw the power demanded of it, regardless of the max capability.
A quality unit will have a 10 year warranty.
Look for Corsair rm units or Seasonic prime or focus units.
Today, a cpu upgrade is in order.
To my mind, the single thread performance of intel 13th gen is compelling.
Run the cpu-z bench on your 8700K.
You should get a rating of 468:
http://valid.x86.fr/bench/pzi81n
The very best will be a I9-13900K if your budget permits.
Here is a review of the 13th gen K series:
https://www.tomshardware.com/reviews/intel-core-i9-13900k-i5-13600k-cpu-review
You will need a lga1700 motherboard, preferably a Z690.
Since ddr3 no longer works, plan on a 2 x 16gb DDR5 ram kit.
Pick a middling speed.
You will need a new cooler for a lga1700 motherboard.
Unless you are an overclocker(not recommended for gaming) A good twin tower air cooler in a good case will do the job simply. Noctua NH-D15 for example.
It is the equivalent of a 240 aio.
The 13th gen processors have more efficient microcode giving more instructions per clock. That results in less heat generated. Games will not fully load all cores.
It is the multithreaded batch apps that can load all cores and could need a 360 aio or better.
This is a good time to upgrade your case.
Look for one with good airflow. Not just for the cpu cooling but also for motherboard vrm cooling and graphics card cooling.
Two 140mm front intakes can do the job.
Some cases will have 200mm front intakes.
Whatever, buy a case with the looks you love.