Change the Cpu to a I5 2500k, you will not see a diference in gaming between I7 and i5 2500k, Get Another brand of Psu Antec and Corsair are good Brands, With your budget you should get at least a 6970 or Going with 2 Gtx 570. or 2 6950
Change the CPU to 2500k...hyperthreading does almost nothing for gaming,
change the cooler to CM 212+(it will get you to 4.5ghz at 1.35-1.38v easily),
get a cheaper motherboard such as the Asrock z68 extreme 3 or even the P67 boards. Also you don't need gen 3...not a single video card right now needs more than x8 pcei gen 2 speeds...Also motherboards within a given chipset perform within 98-100% of each other..even the $300 performs the same as a $120 board if they are using the same chipset. The only difference is features..so make sure you're not spending more for stuff you won't use.
Get an 850W PSU with 70amps on 12v rail..don't worry about those 80+ stickers..its all fraud..manufacturers cherry pick pieces to get the certification. You can get decent brands for $80-$100 in the US.
You need to focus on spending the maximum amt of money on the graphics card....atleast $350-$400 if you ask me because thats the whole point of a gaming system. A good motherboard, good PSU, good cooler, good ram is not going to do anything for gaming when you compare it to a good graphics card. You need at a minimum Radeon 6970 or 2x 6950 2gb or 2 X 7870/7850 (upon release).
For Ram get the cheapest ram thats 8gb...1600mhz...cas 9 or 8...all ram perform the same and have the same chance of going bad...they all come with lifetime warranty. In the US...patriot sells those specs in 4gb x2 for $25 sometimes.
For your SSD try to get an agility 3 or Force 3 or any other 90gb SSd. In the US you can get them for under $100 sometimes. 60gb can cause issues but 90gb is enough capacity for windows+2-3 games+ other applications. Don't go for the caching thing in z68...a pure SSD is insanely better than HDD+SSD combo.
Your case is reasonable but you can save some more perhaps by getting a CM 690 II or cougar evolution...assuming they have deals..still its a decent case. I just think you can get something for under $70-$80 and focus more on the video card.
You guys have way too many taxes in the UK..when I think of 1000 pounds..I think $1500 due to the conversion..which can buy a much better system in the US..but 1000 pounds is more like a $1100-$1200 system with all the taxes in the UK.
That all adds up to £647, im looking for a graphics card for around £300-£350 but im not sure whether to go SLI/crossfire or whether to get a single card, what would you recommend? I was thinking something like :
Can't really find fault with that build.
A few thoughts though:
I would get low profile ram as they won't interfere with cpu coolers. (e.g. corsair vengeance LP)
OCZ branded SSD's apparently are having a few problems and it's better to go for mushkin or crucial.
A single card will most likely give you less problems than a multi card setup but will be less powerful. 2 560Ti's are more powerful than a 580, the only question mark i'd have is the 1GB Vram which will mean you won't be able to crank AA so high as a bigger Vram equipped card would, however if you're running at 1080p i doubt it'd be a real problem. I think OcUK will probably be fine, but most likely won't overclock as well as a more expensive brand.
It does recommend OCZ drives, but be aware that they seem to be more likely to fail.
yeah that ASUS card is a 3 slot rather than 2 slot cooler, your motherboard will support SLI but the fans won't have much room to breathe so a 2 slot cooler would be better, if your sure you want to SLI.