PCPartPicker part list:
http://uk.pcpartpicker.com/p/3u5Lg
Price breakdown by merchant: http://uk.pcpartpicker.com/p/3u5Lg/by_merchant/
Benchmarks: http://uk.pcpartpicker.com/p/3u5Lg/benchmarks/
CPU: AMD FX-6300 3.5GHz 6-Core Processor (£76.79 @ Aria PC)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler (£25.45 @ Scan.co.uk)
Motherboard: Gigabyte GA-970A-UD3P ATX AM3+ Motherboard (£64.79 @ Aria PC)
Memory: G.Skill Ares Series 8GB (2 x 4GB) DDR3-1866 Memory (£63.91 @ Amazon UK)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive (£42.73 @ Aria PC)
Video Card: MSI Radeon R9 270 2GB Video Card (£129.59 @ Aria PC)
Case: Cooler Master K280 ATX Mid Tower Case (£32.58 @ CCL Computers)
Power Supply: EVGA 500W 80+ Bronze Certified ATX Power Supply (£36.76 @ Amazon UK)
Optical Drive: Samsung SH-224DB/BEBE DVD/CD Writer (£11.52 @ CCL Computers)
Operating System: Microsoft Windows 8 (OEM) (64-bit) (£73.83 @ Ebuyer)
Total: £557.95
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-04-18 21:58 BST+0100)