Guides
Power supply guides
Plain-English answers to the questions people ask before buying a power supply, grouped by topic. Each one ends with picks you can buy on Amazon.
Sizing
- Sizing · 6 minHow many watts do I need?Your graphics card decides most of the answer. Here is how to size a power supply properly, with tables, worked examples and the mistakes to avoid.
- Sizing · 3 minIs 750W enough?Which graphics cards run on a 750W power supply, which need more, and when to size up.
- Sizing · 3 minIs a bigger power supply wasteful?Does an oversized power supply waste electricity? What actually happens, how much it matters, and how much headroom is sensible.
- Sizing · 3 minTransient power spikes explainedWhy modern graphics cards draw short bursts of power far above their rating, how that crashes PCs, and how ATX 3.0 power supplies deal with it.
GPU matching
- GPU matching · 5 minThe best power supply for your graphics cardFind your graphics card, see the size you need, and get my pick at that size. Covers RTX 50, RTX 40, RTX 30 and current AMD cards.
- GPU matching · 4 minThe best power supply for RTX 50 series cardsThe size you need for an RTX 5090, 5080, 5070 Ti, 5070, 5060 Ti or 5060, the connector each card uses, and my pick at each size.
- GPU matching · 4 minThe best power supply for AMD Radeon RX 9000 cardsThe size you need for an RX 9070 XT, RX 9070 or RX 9060 XT, which models use the 16-pin plug, and my pick for each.
Standards
- Standards · 5 minATX 3.1 and the 12V-2x6 connector, explainedWhat ATX 3.1 changed, why the 16-pin graphics card plug has a melting problem, and how to fit it safely.
- Standards · 3 minPCIe 5.0 and 5.1 power supplies: what the labels meanWhat “PCIe 5.0 ready” and “PCIe 5.1” mean on a power supply box, how they relate to ATX 3.0 and 3.1, and whether you need one.
- Standards · 3 minWill this power supply fit my case?How to check power supply size against your case, the measurements that matter, and the units that cause fitting problems.
Efficiency
- Efficiency · 5 min80 Plus Bronze vs Gold vs Platinum vs TitaniumWhat the efficiency badges really mean, how much each step up saves, and why Cybenetics ratings tell you more than 80 Plus.
- Efficiency · 3 minCybenetics ratings explained: ETA and LAMBDAWhat the Cybenetics efficiency and noise grades mean, why they are more useful than 80 Plus, and how to read them when you shop.
- Efficiency · 3 minHow much does a power supply cost to run?How to work out what your PC costs in electricity, how much a more efficient power supply saves, and when it is worth paying for.
Build quality
- Build quality · 4 minWhat makes a good power supply?Two units with the same wattage and badge can be very different inside. What separates a good power supply from a risky one, in plain English.
- Build quality · 3 minPower supply protections explained: OCP, OVP, OPP and the restWhat each protection on a power supply box means, which matter most, and why the way they are set matters as much as having them.
- Build quality · 3 minJapanese capacitors in power supplies: do they matter?Why reviews and boxes mention Japanese capacitors, what the 105°C rating means, and how much it matters for your choice.
- Build quality · 3 minSingle rail vs multi rail power suppliesWhat single and multi rail mean on a power supply, whether one is safer, and what it means for plugging in your graphics card.
- Build quality · 3 minWho really makes your power supply?Most power supply brands do not build their own units. What an OEM is, the big names behind the labels, and why it matters when you buy.
Features
- Features · 4 minFully modular vs semi modular vs non modularWhat fully modular, semi modular and non modular mean, which is easiest to build with, and whether it is worth paying for.
- Features · 3 minZero RPM and semi-passive fan modes explainedWhy your power supply fan is not spinning, how fan-off modes work, and which of my picks keep the fan off longest.
- Features · 3 minPower supply warranties explainedHow long power supply warranties run, what they cover and do not cover, and how to make a claim.
- Features · 3 minPower supply cables explained: which cable goes whereThe 24-pin, CPU, graphics card, SATA and Molex cables, what each one powers, and how many a typical build needs.
Buying
- Buying · 5 minThe best SFX power supplies for small buildsSmall cases need small power supplies. How SFX and SFX-L differ, what to check before you buy, and the SFX units worth buying at each size.
- Buying · 5 minDo I need a new power supply when I upgrade my graphics card?Four checks to tell whether your current power supply can handle a new graphics card, with worked examples and what to buy if it cannot.
- Buying · 5 minThe best budget power supplies that are still safeCheap power supplies are where builders get burned. What you give up by spending less, the red flags to avoid, and the budget units I would trust.
- Buying · 5 minThe best quiet power suppliesThe power supplies lab reviewers found quietest, how noise is measured, and how to keep any power supply quieter.
- Buying · 3 minHow long do power supplies last?How many years a good power supply lasts, what wears it out, and when it is time to replace it.
- Buying · 3 minHow to tell if a power supply deal is actually goodHow to judge a power supply discount on Amazon, the traps that make a deal look better than it is, and when to buy.
- Buying · 3 minShould you buy a refurbished or used power supply?The risks of second-hand and refurbished power supplies, what to check if you do buy one, and when it makes sense.
- Buying · 4 minBest 650W PSU (2026): every one worth buyingThe 17 650W power supplies on my list, sorted by the kind of build they suit, with my picks and today’s price on Amazon.
- Buying · 7 minBest 750W PSU (2026): every one worth buyingThe 53 750W power supplies on my list, sorted by the kind of build they suit, with my picks and today’s price on Amazon.
- Buying · 8 minBest 850W PSU (2026): every one worth buyingThe 69 850W power supplies on my list, sorted by the kind of build they suit, with my picks and today’s price on Amazon.
- Buying · 7 minBest 1000W PSU (2026): every one worth buyingThe 57 1000W power supplies on my list, sorted by the kind of build they suit, with my picks and today’s price on Amazon.
- Buying · 6 minBest 1200W PSU (2026): every one worth buyingThe 38 1200W power supplies on my list, sorted by the kind of build they suit, with my picks and today’s price on Amazon.
- Buying · 4 minBest 1300W+ PSU (2026): every one worth buyingThe 21 1300W+ power supplies on my list, sorted by the kind of build they suit, with my picks and today’s price on Amazon.
- Buying · 3 minThe best power supplies on Amazon (2026)My shortlist of power supplies worth buying that you can order on Amazon today, with my pick at every popular wattage.
Install
- Install · 4 minHow to install a power supplyA step-by-step guide to fitting a new power supply or swapping an old one, including which cables go where and the checks before you switch on.
- Install · 3 minPSU fan up or down?Which way to mount your power supply, why it matters, and the one situation where fan up is better.
- Install · 4 minHow to test a power supplyThe ways to check whether a power supply works: a swap, a power supply tester, a multimeter and the jumper test. What each tells you and how to do it safely.
- Install · 3 minChoosing a power supply for a home server or NASWhy a server or NAS needs a different power supply from a gaming PC, and what to look for when it runs all day at light load.
Safety
- Safety · 5 minNever reuse modular cablesThe plugs look the same, but the wiring isn’t. Why the wrong modular cable can destroy your parts, how to tell which cables you have, and what to do if you have already used the wrong one.
- Safety · 4 minGraphics card power adapters: when they’re safe, and when to avoid themThe 16-pin adapter in the graphics card box, 8-pin splitters, angled plugs and cheap SATA or Molex converters. What is fine and what is not.
- Safety · 4 minWhat to do after a power surgeA storm or power cut and now your PC will not start, or acts strangely. How to check it safely, what usually fails, and how to protect it next time.
Problems
- Problems · 6 minSigns your power supply is failingRandom shutdowns, a burning smell or a PC that will not start. How to tell if the power supply is really the problem, how to check safely, and what to replace it with.
- Problems · 4 minPC shuts off under load: is it the power supply?Your PC turns off while gaming or rendering. How to tell whether the power supply is to blame, and what to check first.
- Problems · 3 minPower supply noises: coil whine, clicking and buzzingWhat each noise from your PC means, which ones are normal, and when a noise is a sign to replace the power supply.