Is it worth to upgrade?

[Martynelius]

My current rig:

Mobo: B75MA-P45
CPU: i5-2500k (want to overclock but not possible with current mobo to increase performance)
Cooler: stock
GPU: R7 240
Ram: 8GB DDR3 1600Mhz

Feature upgrade:

Mobo: MAXIMUS VIII HERO
CPU: i5-6600k (going to overclock to 4.5Ghz)
Cooler: Nepton 240m
GPU: R9 390 or GTX 970
Ram: 8GB DDR4 2133Mhz

I've had this rig for around 3 years got it in 2012 and I really love to play games and I want to play Star Wars Battlefront and Star Citizen when they release on ultra 1080p resolution. I can't just buy a new motherboard for the 2500k so I can overclock it because in my country they don't sell motherboards with that chipset anymore. So I need to buy it from another country and because of that the prize can get up to the same prize as a MAXIMUS VIII HERO because for shipping and other things you need to pay for. Motherboards with that chipset is also a bit hard to find at least I struggled with that and some that I managed to find are not even good.
So is it worth to upgrade?

 

[Bungle11]

The i5-6600k is a socket 1151 chip. You can't use DDR3 on it. So you will need to get DDR4 memory with the board you have chosen. You can get cheap 1151 mb's with ddr3 but are they worth it? Perspnally a i7 K on ddr3 will still be my choice.