Just to be sure there won't be any problems I'd change to a mid tower case and mobo, the price will keep the same:
PCPartPicker part list / Price breakdown by merchant
| Type | Item | Price |
|---|---|---|
| CPU | Intel Core i5-4460 3.2GHz Quad-Core Processor | £143.94 @ Aria PC |
| Motherboard | ASRock H97 Anniversary ATX LGA1150 Motherboard | £60.99 @ Amazon UK |
| Memory | Corsair Vengeance 8GB (2 x 4GB) DDR3-1600 Memory | £56.34 @ Aria PC |
| Storage | Crucial MX100 256GB 2.5" Solid State Drive | £73.02 @ Amazon UK |
| Video Card | MSI Radeon R9 290 4GB TWIN FROZR Video Card | £234.48 @ Scan.co.uk |
| Case | NZXT Source 210 Elite (Black) ATX Mid Tower Case | £35.99 @ Aria PC |
| Power Supply | EVGA SuperNOVA NEX 650W 80+ Gold Certified Fully-Modular ATX Power Supply | £63.31 @ Amazon UK |
| Optical Drive | Samsung SH-224DB/BEBE DVD/CD Writer | £10.50 @ CCL Computers |
| Operating System | Microsoft Windows 8.1 (OEM) (64-bit) | £74.34 @ Aria PC |
| Wireless Network Adapter | Asus PCE-N15 802.11b/g/n PCI-Express x1 Wi-Fi Adapter | £15.10 @ Amazon UK |
| Prices include shipping, taxes, rebates, and discounts | ||
| Total | £768.01 | |
| Generated by PCPartPicker 2015-04-06 16:50 BST+0100 |