What Makes A PSU Good

[teddy710]

Buying a PSU but not sure what makes one great and what just makes one good. Can someone explain and give some specs of what makes a good and what makes a great power supply? Thanks!

[Moonzy]

short answer: PSU tier list, jonny guru

 

long answer:

build quality, performance, functionality, and value

though i would put value as my last priorities lol

[WereCat]

Quality components and assembly makes PSU good. Efficiency is just rating and even 80+ Titanium PSU can be total crap. Best to read some reviews before you pick up PSU. Jonny Guru is one of the best sources for this. Anandtech does some nice reviews as well but not in such amount.

[DioOmicida]

http://i.imgur.com/tgrbCnr.jpg
I use this for reference.

[HKZeroFive]

Good voltage regulation, good Japanese capacitors, good ripple suppression...

[STRMfrmXMN]

2 hours ago, DioOmicida said:

http://i.imgur.com/tgrbCnr.jpg
I use this for reference.

The PSU tier list tat @Aniallationmade here is far superior as it doesn't list rebrands as being worse than their original counterpart... 

[quan289]

I'd made this post a while back.
 

Spoiler

 

"The purposed of a power supply is to take AC power from the wall and convert it into DC power that is usable for your components while following a standard specification. How good a power supply is is determine by how well it can output its rated power within those specifications, under what specific condition, and for how long, as well as are the safety protection are operating correctly while doing so. A more expensive PSU might reflect that the PSU is capable of doing it job better and is of higher quality (more reliable and last longer); however, there are many price adders that drive the prices up that can make it more expensive. Because of this, you cannot be sure that what you are getting for a higher price is necessarily better. A higher price could simply mean that the company is confident in their marketing team that they can sell it to you at that price regardless if it is better or not.

 

Here's an example of a bad PSU: http://www.hardwaresecrets.com/article/Cooler-Master-Extreme-2-475-W-Power-Supply-Review/1550

Cooler Master Extreme 2 475. Looking at the testing on page 7-9, you will see that the unit isn't a 475w unit as it burned out at 430w (showing that it lacks an important safety protection). It shows that it offer poor voltage regulation and DC quality output to the point that started to violated ATX specifications above 360w. Now, this doesn't mean all CM PSUs are bad. Many of their newer PSUs ranges from good to excellent such as the Cooler Master V850. It just to show you that you can't rely on the branding alone to determine the quality of an unit.

 

A good entry level unit is the Corsair CX series. Under a certain conditions, it can output what it is rated for extended amount of time continuously while still following ATX specifications. Now I said under specific conditions. The CX is rated for 30C. If you were to put it in an environment that exceeds 30C, the unit may lose its capability to supply its rated output. To give an example of this, Oklahoma Wolf of Jonnyguru.com made a review of the CX750M here. During the cold testing (<~30C), it was able to deliver 750w continuously; however, it was not able to do so on their hot testing where the temperature had went up to 40C.

 

Quality of components. The Corsair CX uses Chinese capacitors from CapXon as well as a sleeved bearing fan, while another entry level PSU like the Seasonic S12II Bronze uses full Japanese caps and a 2BB fan. There's also engineering overhead. There are some PSU out there that over-engineer their PSU, where it can in theory output FAR beyond what it is rated for. Take the Antec Earthwatt Platinum 650w and Antec Signature 650w. At 45-50C, the Antec EwP had shown to be able to output ~775wDC max before shutting off, while the Antec Signature shows 870wDC. Not only did the Signature able to output more, it did it while performing much BETTER than then the Antec EwP. This also shows that a higher efficiency unit does not necessarily mean better quality unit overall.

 

Of course, there's other price adders such as modularity, silence, aesthetics, and other feature sets. I had provide two examples of each brand except for the Corsair, so I'm going to used the AXi series here. It's a fully modular, digital PSUs, that perform brilliantly, offer you the ability to adjust the fan speed, switch between single rail and multi-rail mode, adjust the OCP when in multi-rail mode, monitor the power draw from the wall, to the components, the 12v, etc. It is also manufactured by a server-grade company, Flextronics. It's component choices and overall build quality is top-notch (with the exception of the Yateloon fan that is found in every unit except for the Titanium unit). It's also very expensive, but I'll leave if it is worth it or not for another time."