Did you follow a 3 year old guide or something?
Here:
PCPartPicker part list / Price breakdown by merchant
| Type | Item | Price |
|---|---|---|
| CPU | Intel Pentium G4560 3.5GHz Dual-Core Processor | £51.99 @ Ebuyer |
| Motherboard | MSI B250I GAMING PRO AC Mini ITX LGA1151 Motherboard | £96.98 @ Amazon UK |
| Memory | Corsair Vengeance LPX 8GB (1 x 8GB) DDR4-2666 Memory | £55.00 @ Aria PC |
| Storage | Sandisk SSD PLUS 240GB 2.5" Solid State Drive | £74.80 @ Alza |
| Video Card | Asus Radeon RX 470 4GB STRIX Video Card | £153.54 @ Aria PC |
| Case | Fractal Design Node 202 HTPC Case w/450W Power Supply | £116.40 @ Aria PC |
| Operating System | Microsoft Windows 10 Home OEM 64-bit | £87.00 @ Aria PC |
| Prices include shipping, taxes, rebates, and discounts | ||
| Total | £635.71 | |
| Generated by PCPartPicker 2017-03-28 20:26 BST+0100 |
I don't know if you're set on that case, or if it will even fit all these parts. Think about getting some other Mini-ITX case and a PSU. Throw an extra HDD in there if you need the space.