Processor: Intel Core i7-2600K Quad-Core Processor 3.4 GHz 8 MB Cache TURBO OVERCLOCK
Chiller: ARCTIC Alpine 12 chiller with MX-2 putty
Motherboard: Gigabyte GA-Z77P-D3
Video cards: Gigabyte GTX 960 4GB GDDR5 OC
Ramat: Kingston HyperX FURY 16GB DDR3 2x4GB PC3-12800 1600MHz CL11
Hard Disk: Seagate 1TB+ssd 500GB
Power supply: EVGA 450 BR, 80+ Bronze 450W
Wi-Fi card: TP-Link TL-WDN4800 N900 Dual Band PCI-E Wireless WiFi network Adapter Card for PC
Even if they were socket compatible, you still have to make sure they are chipset compatible, and most important is that the i7-4790K is compatible with the Gigabyte BIOS.
You can solve all of your questions by going to https://www.gigabyte.com/Motherboard/GA-Z77P-D3-rev-11/support#support-cpu
The processor is a 3.4ghz processor. Not the latest, but still good (in my opinion).
You can look at the specs here and decide:
It would all be relative to the games you intend to play.
However, it is an old processor. Upgrading to a new(er) system that is supported on Windows 10 would be a good thing!