You're on a budget, so let's keep it inexpensive, yet efficient, shall we?
The GTX 690 requires a 650W PSU, at least. Ref:
http://www.geforce.com/hardware/desktop-gpus/geforce-gtx-690/specifications
You need the cheapest CPU in tier 1, according to this:
http://www.tomshardware.com/reviews/gaming-cpu-review-overclock,3106-5.html
No need to go any higher in terms of pricing for a CPU to match the 690...
For a 500 pound budget, I suggest:
PCPartPicker part list:
http://uk.pcpartpicker.com/p/Cyjq99
Price breakdown by merchant: http://uk.pcpartpicker.com/p/Cyjq99/by_merchant/
CPU: Intel Core i5-4440 3.1GHz Quad-Core Processor (£131.20 @ Aria PC)
Motherboard: MSI Z97 PC MATE ATX LGA1150 Motherboard (£64.74 @ Aria PC)
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-2133 Memory (£56.91 @ Ebuyer)
Storage: Samsung 840 EVO 250GB 2.5" Solid State Drive (£90.00 @ Aria PC)
Storage: Seagate Barracuda 3TB 3.5" 7200RPM Internal Hard Drive (£69.98 @ Aria PC)
Case: Cooler Master K350 ATX Mid Tower Case (£23.99 @ CCL Computers)
Power Supply: EVGA SuperNOVA NEX 650W 80+ Gold Certified Fully-Modular ATX Power Supply (£63.31 @ Amazon UK)
Total: £500.13
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-01-19 00:11 GMT+0000
Highlights:
You get a lightning fast 250GB SSD,
3TB HDD,
Full modular cabling PSU
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