Question 1

How much wattage do I actually need for a gaming PC?

Accepted Answer

For most gaming builds, 650W–850W is the right range. A system with a mid-range CPU and an RTX 4070 or RX 7800 XT will rarely exceed 400W under load — a 650W Gold unit gives you comfortable headroom. Step up to 850W if you're running an RTX 4080 or 4090, or if you plan to overclock. Going beyond 1000W for a single-GPU consumer build is rarely justified and pushes you into a less efficient operating range.

Question 2

Is 80 Plus Gold worth the extra cost over Bronze?

Accepted Answer

Yes, for most builds — the price gap between Bronze and Gold has narrowed considerably, and the efficiency difference (80% vs 90%) translates to real savings on your electricity bill over time. A PC running 6 hours a day for three years will consume meaningfully less power with a Gold unit. Bronze is acceptable for a budget build you'll use occasionally; for anything that runs daily, Gold is the sensible choice.

Question 3

What's the difference between fully modular and semi-modular PSUs?

Accepted Answer

A fully modular PSU lets you detach every cable, including the 24-pin ATX and EPS CPU cables — useful for the cleanest possible builds. Semi-modular keeps those essential cables fixed but allows you to leave unused PCIe and SATA cables out of the case. In practice, semi-modular is the better value proposition for most builders: you'll always need the fixed cables anyway, and the cost saving over fully modular is real. Fully modular makes most sense in small form-factor or showcase builds where every centimetre of cable routing matters.

Question 4

Do I need a PCIe 5.0 PSU for an RTX 40-series or RTX 50-series GPU?

Accepted Answer

Not strictly required, but strongly recommended. RTX 40-series and newer GPUs use a 16-pin 12VHPWR connector, and many PSUs supply this via an adapter from two 8-pin cables. These adapters have a documented history of connector damage under sustained load. A PSU with a native 12VHPWR output — labelled PCIe 5.0 ready — eliminates that risk entirely. Given that PCIe 5.0-native units are now available from 78 £ upwards, there's little reason to accept the adapter compromise on a new build.

Question 5

Are cheap no-name PSUs worth the risk?

Accepted Answer

No — a substandard PSU is the one component that can take everything else with it when it fails. Unlike a slow hard drive or a mediocre GPU, a PSU that fails catastrophically can damage your motherboard, CPU, and storage simultaneously. Stick to brands with a credible track record: be quiet!, Seasonic, Corsair, and MSI all have established RMA processes and consistent quality control. The saving on a no-name unit rarely exceeds £15–20 compared to a reputable entry-level option, and the risk profile is entirely different.

Question 6

What does MTBF mean on an industrial PSU, and should I trust it?

Accepted Answer

MTBF (Mean Time Between Failures) is a statistical reliability figure, not a guarantee of lifespan — a unit rated at 200,000 hours MTBF won't necessarily run for 22 years. It's a comparative metric: higher MTBF indicates better component selection and design margins. For industrial applications running 24/7, look for MTBF figures of 200,000 hours or above, as found in Phoenix Contact's QUINT series. For consumer PC PSUs, warranty length (5–10 years from brands like Seasonic and be quiet!) is a more practical reliability indicator.

Question 7

How do I know if my PSU is causing system instability or crashes?

Accepted Answer

Random reboots, blue screens under load, and system crashes that don't correlate with software issues are classic PSU warning signs. The most reliable test is to run a stress tool like Prime95 combined with a GPU load (FurMark) whilst monitoring voltages with HWiNFO64 — the 12V rail should stay within ±5% of 12V. Significant voltage sag or ripple above 100mV under load points to a failing or undersized PSU. If your system is stable at idle but crashes during gaming, the PSU is the first thing to investigate before replacing other components.

Power Supply Units Price Comparison

ASUS TUF Gaming 750W Gold power supply unit 20+4 pin ATX ATX Black

ASUS ROG Loki SFX-L 750W Platinum power supply unit 20+4 pin ATX Black, Silver

ASUS ROG Loki SFX-L 850W Platinum power supply unit 24-pin ATX Black, Silver

ASUS TUF Gaming 850W Gold power supply unit 24-pin ATX ATX Black

ASUS ROG Loki SFX-L 1000W Platinum power supply unit 24-pin ATX Black, Silver

ASUS TUF Gaming 1000W Gold power supply unit 20+4 pin ATX ATX Black

MSI MAG A650BN UK PSU '650W, 80 Plus Bronze certified, 12V Single-Rail, DC-to-DC Circuit, 120mm Fan, Non-Modular, Sleeved Cables, ATX Power Supply Unit, UK Powercord, Black'

MSI MAG A550BN UK PSU '550W, 80 Plus Bronze certified, 12V Single-Rail, DC-to-DC Circuit, 120mm Fan, Non-Modular, Sleeved Cables, ATX Power Supply Unit, UK Powercord, Black'

ASUS ROG Loki SFX-L 850W Platinum White power supply unit 24-pin ATX

MSI MAG A750GL PCIE5 power supply unit 750 W 20+4 pin ATX ATX Black

MSI MAG A650GL power supply unit 650 W 20+4 pin ATX ATX Black

be quiet! Dark Power Pro 13 | 1300W power supply unit 20+4 pin ATX ATX Black

be quiet! Dark Power Pro 13 | 1600W power supply unit 20+4 pin ATX ATX Black

ASUS TUF GAMING 1200W Gold power supply unit 20+4 pin ATX ATX Black

MSI MAG A850GL PCIE5 power supply unit 850 W 20+4 pin ATX ATX Black

ASUS TUF Gaming 1000W Gold White Edition power supply unit 20+4 pin ATX ATX

MSI MAG A750BN PCIE5 power supply unit 750 W 24-pin ATX ATX Black

ASUS ROG -LOKI-1200T-SFX-L-GAMING power supply unit 1200 W 20+4 pin ATX Black, Silver

Seasonic Focus GX power supply unit 750 W 20+4 pin ATX ATX Black

Seasonic Focus GX power supply unit 850 W 20+4 pin ATX ATX Black

VIDA ATX-500W-WHT power supply unit 20+4 pin ATX White

be quiet! PURE POWER 12 850W power supply unit 20+4 pin ATX ATX Black

ASUS ROG -STRIX-1200P-GAMING power supply unit 1200 W 20+4 pin ATX ATX Black

be quiet! PURE POWER 12 650W power supply unit 20+4 pin ATX ATX Black

Power Supply Units Price Comparison