Power Supply

Introduction

The power supply (AKA the PSU) is the thing that pulls scary-dangerous 240V AC from your wall and converts it into several DC rails with different voltages for each of your parts to happily use.

Often an overlooked and grossly under-budgeted part in novice builders, the PSU does its work and never complains about it. A little investment in your PSU can go a long way for your power bill!

Picking your PSU

80+ cardboard? Fluid-bearing fans? High Current GAMER?!

Confusing terminology often leads to switched off brains purchasing cheap PSUs that will spectacularly fail in under 3 years, taking their whole rig down with it.

Luckily for you, there's a LTT PSU Tier List!

Anything Tier 1/2 are highly recommended and will last you 5+ years! Avoid anything below Tier 3 unless you're on a really, really tight budget.

Wattage

You will need to ensure your PSU delivers sufficient power to your system under load. 600W is sufficient for most single graphics card systems, but when in doubt opt for more watts.

Insufficient wattage may cause your system to power off under load, which would be very unfortunate if you haven't saved your work or are in the middle of the finals of an online gaming competition.

Do note that power supplies will slowly lose wattage over time as they degrade, so if you wish your PSU to last it is best to buy one with slightly more wattage than you need at the time of purchase.

Modularity

This refers to the ability to remove cables that aren't needed from the PSU.

Fully modular: All cables can be removed.
Semi-modular: Some cables can be removed (but usually not essentials such as the CPU and motherboard cables).
Non-modular: No cables can be removed. Your only option for managing unneeded cables is to hide them somewhere within the case.

Other considerations

Size: Regular ATX PSUs are generally fine but in smaller cases that take ATX, be wary of length. There are also small cases that take other form factors like SFX and TFX, but they come at a premium!
Noise: Most good PSUs today have a load threshold to completely turn off the fan (the first to do it were the Corsair RM series, then Seasonic followed with a completely passively cooled SKU!). Look out for these in your silent builds!
Longevity: It's not uncommon to see 3 year warranties but look out for the higher tier PSUs that offer 5, or even 7 year warranties!
Price: Your PSU should be roughly 10% of your budget (for consumer-grade components). Any less and you're making compromises that should not be made!

Community Picks

Vincent: I personally have owned a CM 750W Bronze something or other (now retired to my closet) and am still using a RM650 for over 2 years without any hiccups! Here are my picks:

RM550x is a great price/performer clocking in at around $130. With the recent power efficiency jumps across industry, 550 is the new 650!
Seasonic 520 Fanless, almost anything from Seasonic really! Great company with great reputation (hi I'm Sabine and I second this)

Sabine: I've personally owned an EVGA SuperNOVA 650 G2 and a Seasonic M12II-750 and I give a glowing recommendation to both