Is this just a gaming pc ? Are you going to do anything else on it i.e Video Editing/Rendering etc ?
I would go with the 960 EVO over the SM951. It has slightly less capacity (500GB vs 512GB) but it has faster read/write speeds and an extra 1 years warranty.
Do you need such an expensive board ? If you are going to drop £300 on a board then I would go X99 instead.
Some of those big air coolers can block off the top pcie slot. Not sure what the R1 Ultimate is like for that, but I would try and find out first.
If you do go with it then you would need a different case as it is too big for the Inwin 303. Max height stated is 160mm and the R1 is 168mm. It would fit in the 400C and Define S that you linked.
If you don't plan to SLI then you only really need a 550W psu.
Mainly, yes. That said, I do use Fusion 360 which is a CAD program and I would presume be CPU / RAM heavy.
I would like at vids at a point but my wife's iMac is probably better suited anyways.
Thanks for the advice on the storage, that is what I was looking for. I saw the 256G one but its like 90% of the price and similar speed to the 512GB one, but didnt see the 960 EVO.
Expensive board, no, I would like something that works, is reliable (ive had bad issues with Asus before and stopped buying their stuff, but these boards get good reviews). So happy to look at alternatives.
550W only? I suppose today's systems are more effecient. Seems like less about clock speed and more about efficiency with today's CPUs?