Ive spec’d a few builds around that price (This is my PC http://uk.pcpartpicker.com/p/3jr4f7), for the money you are spending id go with this http://uk.pcpartpicker.com/p/gTP2yc. Looking on logical increments ( http://www.logicalincrements.com/ ) you’re going to be looking at a 4K PC really, with 2 GPUs.
I didnt go with a water cooler as i assume youre not going to be Overclocking and both your cards are air coolers so the noise they produce will trump anything else in your case.
CPU, for me Skylake has no tangible benifits over Haswell Refresh other than you pay more for RAM, Mobo and the Chip.
Mobo, ASUS probably the best manufacturers of motherboards, the software that comes with it is so user friendly and easy to use, that said you could upgrade it for a motherboard with more features.
RAM, good RAM you wont be needing more than 16GB and you wont really notice a difference with a higher frequency.
SSD, 250GB enough for your OS and some games with the HDD being 2TB for movies, music etc.
GPUs, @Freebird is the only person i know with one, and he loves it great card, if you want to be playing the most recent titles at 4K you’ll be needing two as one just falls short, two though is more than enough and should see through past the Pascal GPU release next year. SLI isnt at all hard to use either so i wouldnt worry about that, I didnt have an SLI setup until this year and its easy to setup and maintain.
PSU, you cannot really go wrong with corsair, life time warrenty, has corsair link enabled so you can check your wattages if you care for that kind of thing. Modular so it saves mess in the back of your case, while allowing you to get nice sleaved cables if you so desire.
Case, if i were you id look at some and pick the one you like, itll be in your house etc, so me picking a case that i like doesnt really make much sense, that said i put in an Air 540 which is very nice case in my eyes, dual chamber so it hides your PSU and drives.
Monitor, again @Freebird has this monitor and uses it everyday, i know he likes it but im sure if you asked him he could tell you in more detail. Has no ghosting and is 60Hz.
It is over budget by £150-£200 but the ability to play 4K video, 4K games and browse in 4K is worth the extra speaking from my own experiences.