The
system guides here are pretty good places to start.
Sites:Scan.co.uk is a great site, though you could end up spending at least £50 more than the same build at ebuyer.
Ebuyer.com is probably the cheapest place and with free shipping.
Overclockers.co.uk, Novatech.co.uk and Dabs.com are all worth looking at too, sometimes there are great deals there.
Changes to the TR Sweet Spot build:You don't need to spend £1500, nowhere near that in fact - The "sweet spot" as listed should set you back about £800 over here without screens. The upgrade to an i5-3570K makes sense - you can pretty much choose any cooler you want if you're going to overclock but the Coolermaster Hyper 212 is good value, as is the Arctic Cooling Freezer 7. Overclocking the 3570K is as easy as going into the BIOS and setting the turbo multiplier to 42. Sure, you can overclock more than that but 4.2GHz should be more than fast enough for gaming and it's pretty unlikely that a 3570K won't reach this on stock voltage. You can also run the "auto overclock" utility included with the motherboard drivers if you don't even want to fiddle with the BIOS.
Audio:I would skip the Xonar audio since pretty much everything runs without feature or quality loss on the most basic of audio codecs, even those built into things like USB headphoness.
Screens:As for screens, a Korean 27" from ebay for about £250 is what I'm using now and I prefer it to all the 120Hz gaming panels I've seen. If you want to get an idea for how it looks, wander into an Apple store and look at the 27" Thunderbolt display and then wander into a Dixons/Currys and look at the TN gaming screens. Getting a game to run fluidly at 120 frames a second is a lot harder than you'd expect, often you have to sacrifice a lot of the graphics settings so I would instead aim for 60FPS at the highest quality possible instead. UK buyers seems to be positive about the ebay seller called TA Planet who does the basic Shimian QH270-Lite for about £200 (£40-odd import duty).
CaseI see you're getting a large case, big PSU and full ATX board for potential future SLI upgrades; There's no reason to do this unless you genuinely want more than about six drives;
Upgrading to a more powerful graphics card is usually better than running two of them - you will avoid any SLI/Crossfire performance penalties, micro-stuttering is still a problem for dual-GPU solutions and two cards generate twice as much heat and noise whilst sucking down more power (and requiring a beefier PSU).
Sticking to a single card also means you can get a smaller case and motherboard which typically means it's quieter because less air needs to be moved to completely cycle all of the hot air out of the case.
One of the best, coolest, quietest cases on the market is the
Silverstone TJ08B-E, which is a positive-pressure system and shouldn't need you to buy any extra fans. However, the Fractal Define Mini or Arc Mini are also excellent choices.
My suggestion:£175.25 = Intel Core i5 3570K - easy overclocking
£79.42 = Asus P8Z77-M Z77 - good basic mATX board with solid capacitors and no silly features.
£24.99 = Crucial 8GB (2x4GB) DDR3 1600Mhz Ballistix 1.5V 9-9-9-24 - Intel/Micron's own-brand memory, which is plenty good enough.
£80.00 = SAMSUNG 128GB 830 Series SSD - One of the best drives, you could get a 256GB if you fancy it (better cost/GB)
£54.99 = 1TB Western Digital Caviar Black - If you're just using it for media storage, perhaps get a 2TB Seagate 5900rpm drive.
£239.99 = Sapphire HD 7950 3GB Boost (925MHz) - Competitive with the GTX670 but you get more free games, it's significantly cheaper, and this model has good quiet fans.
£69.99 = Be Quiet Pure Power 630W Modular PSU - Honestly, you could get away with a 450W PSU. This is quiet, well-made, well-reviewed, modular and has adequate headroom for upgrades.
£69.99 - W7 Home Premium w/SP1 x64 OEM - Assuming you don't already have a license you can transfer.
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£795 total from Ebuyer and then picking up a Silverstone TJ08B-E case from wherever it's cheapest.
Obviously chop and change parts as desired, this is just my recommendation and I'm sure it'll be one of many in this forum.