Here is the components for £496.56.
PCPartPicker part list:
http://uk.pcpartpicker.com/p/2Row2
Price breakdown by merchant: http://uk.pcpartpicker.com/p/2Row2/by_merchant/
Benchmarks: http://uk.pcpartpicker.com/p/2Row2/benchmarks/
CPU: AMD FX-6300 3.5GHz 6-Core Processor (£80.39 @ Aria PC)
CPU Cooler: Zalman CNPS10X OPTIMA CPU Cooler (£16.31 @ CCL Computers)
Motherboard: Asus M5A97 R2.0 ATX AM3+ Motherboard (£63.99 @ Amazon UK)
Memory: Kingston HyperX 8GB (2 x 4GB) DDR3-1600 Memory (£62.00 @ Amazon UK)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive (£39.98 @ Aria PC)
Video Card: XFX Radeon HD 7870 GHz Edition 2GB Video Card (£139.99 @ Aria PC)
Case: Zalman Z9 ATX Mid Tower Case (£36.98 @ Dabs)
Power Supply: XFX 550W 80+ Bronze Certified ATX Power Supply (£45.00 @ Aria PC)
Optical Drive: Samsung SH-224DB/BEBE DVD/CD Writer (£11.92 @ CCL Computers)
Total: £496.56
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-02-11 17:39 GMT+0000)