Honestly, as much as I like AMD, I cannot recommend the 860K at all, not with Zen just around the corner & even though I OWN a system with the 860K in it. You will literally be throwing good money after bad if you do.
I like it, it's a decent enough chip, but there is no upgrade path from it & that makes it almost worthless in a new build.
My recommendation, if you are going cheap and don't plan on overclocking is something along the line of this:
Intel Skylake Core i3 6100: https://www.amazon.co.uk/Intel-BX80662I36100-Skylake-Dual-Core-Processor/dp/B015VPX2EO £92.91 (Yes I know it's dual core, but it will still outperform the Athlon 860K, plus you can upgrade from it without having to change the motherboard
Gigabyte H110M-S2H Micro ATX motherboard https://www.amazon.co.uk/Gigabyte-H110M-S2H-Motherboard-Socket-Express/dp/B01649KMZS/ref=pd_bxgy_147_img_2?ie=UTF8&psc=1&refRID=H9PQ7YYPRAMB8A95E94S £51.61
8GB HyperX Fury RAM DDR4 https://www.amazon.co.uk/HyperX-Mem...g_3?ie=UTF8&psc=1&refRID=H9PQ7YYPRAMB8A95E94S £35.05
Total cost of £179.57 or around 207 Euro
Changing the i3 6100 for an i5 6500 ups the price to around £300, the extra performance is worth it (if you can afford the cost) but the i3 will still outperform an 860k in all respects at 1080p.
Your 860K build would cost around the same but have DDR3 Memory instead and no upgrade path.
As much as I hate to say it, I'd go for Intel at this point in time.
I have a little bit of a change to my ideal specs for this mini build, especially if you want to stay with AMD GPU's in the future, Swap out my original motherboard for this one:
https://www.amazon.co.uk/Gigabyte-H...g_2?ie=UTF8&psc=1&refRID=H9PQ7YYPRAMB8A95E94S it costs a grand total of £5 more but allows for 4 memory slots & crossfire, that makes it a tremendously good value board. You will still miss overclocking, but other than that it's a far better choice.