My first build

looks good

CPU for gaming intel 3570k or intel xeon 1230V2.

Intel MoBo? No gigabyte or asus. asrock extreme 4 is good too. but asus and gigabyte has year longer warranty.

radeon? 7950 from asus or gigabyte. they have best cooler systems in video cards.
PSU 750w from seasonic or corsair are good. bronse,gold,platium labeld are good.

Cooler: H100 / H100i is better.

That case is not best one.

No reason to purchase an i7 or a Xeon for a gaming rig. No reason to purchase a closed liquid loop either when a strong air fan will give you the same overclocking results. Also pay more for a better case - don't go cheap in this area. Here's what I would suggest for that budget:

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: Intel Core i5-3570K 3.4GHz Quad-Core Processor (£164.99 @ Aria PC)
CPU Cooler: Noctua NH-U9B SE2 37.9 CFM CPU Cooler (£36.86 @ Ebuyer)
Motherboard: ASRock Z77 Extreme4 ATX LGA1155 Motherboard (£101.98 @ Dabs)
Memory: Mushkin Blackline 8GB (2 x 4GB) DDR3-1600 Memory (£41.99 @ Aria PC)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive (£57.59 @ Amazon UK)
Video Card: Gigabyte GeForce GTX 670 2GB Video Card (£299.99 @ Amazon UK)
Case: NZXT Phantom 410 (White) ATX Mid Tower Case (£78.90 @ Scan.co.uk)
Power Supply: SeaSonic S12II 620W 80 PLUS Bronze Certified ATX12V / EPS12V Power Supply (£78.53 @ Amazon UK)
Optical Drive: Lite-On iHAS124-04 DVD/CD Writer (£12.98 @ Scan.co.uk)
Total: £873.81
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-02-06 18:42 GMT+0000)