Building a Budget Mini-ITX Small Form Factor PC with Used Parts (UK 2026 Guide)
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There is a common misconception that Small Form Factor (SFF) PC gaming is exclusively an expensive enthusiast pursuit. New boutique ITX chassis like the FormD T1, Louqe Ghost S1, or Lian Li A4-H2O often cost £160 to £240 alone, while new Mini-ITX motherboards routinely command a 50% premium over their standard ATX counterparts—a phenomenon known as the notorious “ITX Tax.”
However, by strategically tapping into the UK second-hand market, you can construct a whisper-quiet, console-sized 1080p/1440p gaming rig for under £450. The secret is knowing which versatile cases accommodate affordable components without requiring bespoke custom liquid loops or fragile PCIe riser cables.
The £450 Complete Budget ITX Bill of Materials
| Part | Hardware Selection | Source | UK Cost |
|---|---|---|---|
| Mini-ITX Case | Cooler Master NR200 / NR200P (18 Litres) | Used Case (eBay/Gumtree) | £35 – £45 |
| Processor (CPU) | AMD Ryzen 5 5600 (6 Cores, 65W TDP) | Used CPU | £55 – £68 |
| Motherboard | ASRock B550M-ITX/ac or Gigabyte B550I AORUS | Used Mini-ITX Board | £75 – £95 |
| Graphics Card (GPU) | Radeon RX 6600 8GB or RTX 2060 Super 8GB | Used GPU | £125 – £145 |
| Power Supply (PSU) | Cooler Master V650 SFX Gold or Corsair SF450/SF600 | Used SFX PSU | £45 – £60 |
| RAM & Storage | 16GB DDR4-3200 + 1TB NVMe PCIe 3.0/4.0 SSD | Used Storage/Memory | £45 – £55 |
| CPU Cooler | Thermalright Assassin X 120 Refined SE | New / Open Box | £17.00 |
| Total Build Cost | Complete 1080p/1440p Console-Sized Gaming PC | £397 – £455 | |
For case sizing recommendations, read our guide on Buying a Used PC Case in the UK.
How to Beat the “ITX Tax” on Used Hardware
Sourcing components for a small form factor build requires different strategy than standard ATX towers:
While Intel LGA1700 ITX motherboards remain stubbornly priced above £120 used, AM4 B450 and B550 ITX boards (like the ASRock B550M-ITX/ac or MSI B450I Gaming Plus AC) frequently sell for £75-£90. Paired with a £60 Ryzen 5 5600, it cuts motherboard/CPU platform costs in half.
A new Corsair SF750 costs £155. On the used market, older gold-rated models like the Cooler Master V650 SFX or Corsair SF600 Gold trade for £45 to £60. Always verify that all short-length SFX modular cables are included in the box!
Thermal Physics in Small Cases: Chimney Effect vs Negative Pressure
In an 18L case like the NR200, configure two 120mm fans at the top as exhaust, and pull fresh intake air directly from the vented bottom and side panels. Because the GPU fans sit less than 15mm from the bottom ventilation holes, graphics cards draw outside ambient air directly, maintaining whisper-quiet operation under 68°C.
Frequently Asked Questions
Can I use a standard ATX power supply in the NR200?
Yes! Cooler Master provides an official 3D-printable ATX PSU bracket (also sold on eBay for £8). However, using a full-sized ATX PSU restricts your maximum graphics card length to under 240mm. An SFX power supply is highly recommended.
Is cable management difficult in a budget SFF build?
In sub-12L cases, custom-length unsleeved cables are almost mandatory. However, in the 18L NR200, the space behind the front panel and next to the SFX power supply cage provides ample room to tuck excess factory cabling using zip ties.
Can this £450 build run modern games at 1440p?
Yes. The Radeon RX 6600 8GB comfortably achieves 60+ FPS at 1080p Ultra and 55–65 FPS at 1440p Medium with FSR upscaling enabled.
Source Mini-ITX & SFF Parts on Koukan
Trade rare Mini-ITX motherboards, SFX power supplies, and compact cases with escrow buyer protection.
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