PC Specialist Gaming rig for £999 - thoughts or alternatives?

Time is a killer for me right now so I have decided to go pre-built rather than faff around myself. I am taking a look at a lot of pre-built gaming rigs to see what I can get for around a grand ( I may be able to sneak over a little bit but not much )

This particular one has caught my eye from PC Specialist at £999

Case CORSAIR 230T COMPACT GAMING CASE - RED LED + SIDE WINDOW
Overclocked CPU Overclocked Intel® Core™i5-4670k Quad Core (3.40GHz @ max 4.20GHz)
Motherboard ASUS® Z87-A: ATX, USB3.0, SATA6GB/S, SLi, XFIRE
Memory (RAM) 16GB KINGSTON HYPER-X BEAST DUAL-DDR3 2400MHz X.M.P (2 x 8GB KIT)
Graphics Card 3GB AMD RADEON™ R9 280X - DVI, HDMI, DP - DX® 11, Eyefinity 4 Capable
1st Hard Disk 120GB KINGSTON HYPERX 3K SSD, SATA 6 Gb/s (upto 555MB/sR | 510MB/sW)
2nd Hard Disk 1TB 3.5" SATA-III 6GB/s HDD 7200RPM 32MB CACHE
1st DVD/BLU-RAY Drive 24x DUAL LAYER DVD WRITER ±R/±RW/RAM
Power Supply CORSAIR 650W RM SERIES™ MODULAR 80 PLUS® GOLD, ULTRA QUIET
Processor Cooling CoolerMaster Seidon 120M High Performance CPU Cooler
Thermal Paste ARCTIC MX-4 EXTREME THERMAL CONDUCTIVITY COMPOUND
Sound Card ONBOARD 6 CHANNEL (5.1) HIGH DEF AUDIO (AS STANDARD)
Wireless/Wired Networking 10/100/1000 GIGABIT LAN PORT - AS STANDARD ON ALL PCs
USB Optionss MIN. 2 x USB 3.0 & 4 x USB 2.0 PORTS @ BACK PANEL + MIN. 2 FRONT PORTS
Power Cable 1 x 1 Metre UK Power Cable (Kettle Lead)
Operating System Genuine Windows 8.1 64 Bit - inc DVD & Licence

I've got a few questions surrounding it which I'm not too sure on that I am hoping you might be able to help with;

Firstly the i5 processor, it's going to be overclocked, but from what I have read it isn't a huge difference getting the i7 but this is a lot cheaper. Is this correct or will the i7 & make a big difference? I'm also worried about overheating. I've never had an overclocked PC before and my study gets warm in summer, will this rig overheat or do you think there is enough cooling there?

Secondly the memory, will 2.4K Ram really make a difference?

Lastly does anyone have experience of these guys? They seem to come out OK on the reviews side of things!

Any thoughts as to any alternatives that give good bang for buck would also be appreciated and thanks in advance!

I believe the overclocked i5-4670k is better for gaming (10 fps diff at most) though I honestly don't think that cooler will cut it so I think that needs to be upgraded
2400MHz makes no real difference (1 fps) so go for 1600MHz
Friend used PC Specialist to buy a £1k PC like you and he was totally happy with the PC and service

seems fine for a prebuild, would you be doing upgrades to it later or just buy a new build? I would ramp up the psu to 750 incase you want to add things in later.

The PC looks as good as its going to be when going prebuilt. This looks fine to me.
Edit: I realised that the OP posted 2 months ago. Oops

this is already a great build... I have z97 gaming 5 with a r9 290 MSI...

in stead of the water cooling set from coolermaster you can also choose for this one:

http://www.watercoolinguk.co.uk/p/Ma...FMx_49872.html

if you take this set, you can also add a GPU block to the loop without having to buy a new set.

Seems a pretty decent build. Hope you enjoy it.