Let me break this up so it's a little easier to read:
1. There is only one benefit in choosing the RAM you chose, and that is aesthetics. It's slower (albeit only slightly for gaming purposes), more expensive, and prohibits easy expandability (a hallmark of PC gaming), but it'll sure look nice. If that's what OP wants, we can't really stop him, but I would never suggest filling all the RAM slots if you don't have to (unless you only have two and you need dual-channel memory for integrated graphics).
2. I didn't say he'd need 32GB of RAM now. In fact, 16 is overkill for most purposes, but you can get 16 gigs for pretty cheap nowadays so we both went that route. But why spend more money on slower RAM that makes you pay more later on when you decide to upgrade?
3. It's fairly clear he doesn't need to overclock now, but several years down the road when his CPU is showing its age, with my build he could crank up the clocks and voltage and play games on ultra again. If he tried that PC MATE board, he might just start a fire because the voltage regulation on PC MATE boards is not that great.
4. There is a point at which adding more case fans doesn't do anything, and that point is pretty early on (like after two or three fans). In fact, the H440 comes with three fans in the front and a fan in the back, so my guess as to why OP included the Corsair fan in his build is he wanted a little case lighting. I don't think he'll need it, but if he wants to spend a little on aesthetics that don't hamper performance or expandability, I won't stop him. The 212 EVO will let that i7 overclock and remain cool whether there are two fans in his case or ten, and the GPU is gonna run hot no matter what unless you put it under water. Here's a video that explains this better than I could:
If we cut out the LED fan OP put in his build and swap the i5 out for an i7, we get a build that's still cheaper than what he originally started with:
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel Core i7-6700K 4.0GHz Quad-Core Processor (£260.28 @ Aria PC)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler (£26.99 @ Novatech)
Motherboard: MSI Z170A GAMING M5 ATX LGA1151 Motherboard (£127.54 @ More Computers)
Memory: Corsair Vengeance LPX 16GB (2 x 8GB) DDR4-2400 Memory (£53.99 @ Ebuyer)
Storage: Sandisk Ultra II 480GB 2.5" Solid State Drive (£96.79 @ Amazon UK)
Case: NZXT H440 (Black/Red) ATX Mid Tower Case (£92.70 @ CCL Computers)
Power Supply: EVGA SuperNOVA GS UK 550W 80+ Gold Certified Fully-Modular ATX Power Supply (£72.78 @ CCL Computers)
Monitor: Asus VS248HR 24.0" 60Hz Monitor (£105.89 @ CCL Computers)
Keyboard: Corsair Raptor K30 Wired Gaming Keyboard (£34.99 @ Amazon UK)
Other: RX 480 (£200.00)
Total: £1071.95
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-06-14 00:03 BST+0100
It has one of the latest i7's, it runs cool, it can overclock well, and it's easy to upgrade. What more could you want?