Need to upgrade my CPU

[PandaChef]

I want to buy BF4 but my CPU isn't good enough to play it. My PC build is 5 years old but I did upgrade the GPU 1 and a half years ago. Here is my build?

WD 1TB Blue Desktop Drive 3.5" SATA-III 7200RPM 64MB
Crucial 8GB (2 x 4GB) DDR3 1333MHz
Corsair CX 600W
AMD Phenom II X4 955 Black Edition Socket AM3 3.2 GHz 6MB
Asus M4A88T-M 880G Socket AM3 Onboard Graphics 8 Channel Audio mATX Motherboard
MSI R9 280X GAMING 3GB GDDR5 DVI HDMI DisplayPort PCI-E Graphics Card

I don't need a really high end CPU and I am not sure how much they cost these days. My current one cost £80 at the time, so guidance would be helpful. What CPU should I get and do I need to replace my motherboard as well?

Thanks.

 

[PandaChef]

Might want to edit out them links?

Huh? The links work fine for me?

The CPU is £220 Intel BX80662I56600K Core i5-6600K LGA1151 3.5 - 3.9 GHz CPU

The MB is £107: MSI Z97 Gaming 3 Intel LGA1150 Z97 ATX Motherboard (4x DDR3, 6x USB3.0, 6x USB2.0, GBE, LAN, HDMI, DVI, DP, VGA)