Gaming PC Build for £700

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: Intel Core i5-4670K 3.4GHz Quad-Core Processor ($199.99 @ Microcenter)
Motherboard: ASRock Z87 Extreme3 ATX LGA1150 Motherboard ($139.98 @ SuperBiiz)
Memory: Corsair Vengeance 8GB (2 x 4GB) DDR3-1600 Memory ($68.99 @ Newegg)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($69.99 @ Amazon)
Video Card: MSI GeForce GTX 770 2GB Video Card ($399.99 @ NCIX US)
Case: Cooler Master Elite 350 ATX Mid Tower Case w/500W Power Supply ($56.57 @ NCIX US)
Power Supply: Corsair Builder 600W 80 PLUS Bronze Certified ATX12V Power Supply ($37.99 @ Newegg)
Optical Drive: Samsung SN-208DB/BEBE DVD/CD Writer ($18.99 @ Newegg)
Optical Drive: Samsung SN-208DB/BEBE DVD/CD Writer ($18.99 @ Newegg)
Total: $1011.48
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-06-08 11:56 EDT-0400)

Perfect build. £700 = $1066.

This one costs around $1011. In your budget, but really strong. :)