How to Pick the Right Power Supply

[Brink]

The Role of the Power Supply

The power supply is an oft-underappreciated component. Everyone knows it’s necessary, and most people who build their own PCs have some understanding of the basics of what a power supply does. But almost everyone tends to buy more power than they really need, or they’ll buy the cheapest PSU that delivers the wattage they think they need.

We’re not going to get too deep into the inner workings of the PC power supply, but it’s worth talking a bit about the basics of how they work before we dive into what to buy. Note that all references to household current are U.S. numbers, so adjust accordingly if you’re reading this in a different part of the world.

Read more at:
Maximum PC | How to Pick the Right Power Supply

 

[sygnus21]

Seeing that this is a sticky I'd like to add some links from my Tips on Troubleshooting Game Issues guide.

Info on power supplies …

- Everything You Need to Know About Power Supplies | Hardware Secrets
- How to Buy a Power Supply - wikiHow

And if you're looking for a good place to review power supplies look here - JonnyGURU.com

 

[Brink]

 

[GeneO]

Who really makes your power supply?

http://whirlpool.net.au/wiki/psu_manufacturers

PSU Review Database

 

[Big Tom]

this thread was a great read. thanks

 

[trevolution11]

Truth is...

It happened to me, I bought a 680w PSU thinking I knew more than I did about them. Didn't offer enough amperage on the 12V rail for my GPU (only pushed 24A). I ended up having to buy another one (Corsair Enthusiast Series 750TX V2) to make up for the one that wouldn't even boot my new build. Lost out on 60 bucks. Lesson learned: Do your research before buying a product - even if you think you know enough to make it happen.

Anyway, check out the GURU. They know what they're talking about.

The "power supply FAQ" - jonnyGURU Forums

 

[Greenfire]

I highly recommend checking out Newegg's wattage calculator before buying a new power supply.

Newegg.com - Recommended Power Supply Calculator.

 

[edwardallene]

Most users won't need to get that detailed, as the wattage and amperage issues are the most important and can be estimated. The other key issue is that you get what you pay for, and that means that you need to find a good brand and avoid the "sale" white-box power supplies that you often see in computer shops. Check every details on it and be more observant on what you buy.

 

[Kipper]

A few of my Power Supply reviews are listed in the Review Data base.

First I heard of this resource was today.

 

[kefah]

thank u man that was very useful

 

[ICIT2LOL]

Now I have read through this and am still have a query that I did not see an answer for (I probably did but....) is then a modular PSU in reality a multiple 12v+ rail PSU if there are more than say two module power sockets carrying 12v+ in addition to the main cable that has the 24pin connector on it and flying cables?

I used a single rail Corsair HX 650 on the last build going on what Scott Mueller stated in his build video and book about having a single rail PSU as being the preference - against a twin or multiple 12v+ rail unit.

I am just curious because if the modular PSU is a single rail then the modules would have to be supplied by the main rectification unit (internally connected) that supplies the flying cables as above making it as stated by Corsair a single 12v+ rail PSU. So in essence making it modular just saves on more flying cables having to be tucked away unused.

 

[ignatzatsonic]

Now I have read through this and am still have a query that I did not see an answer for (I probably did but....) is then a modular PSU in reality a multiple 12v+ rail PSU if there are more than say two module power sockets carrying 12v+ in addition to the main cable that has the 24pin connector on it and flying cables?

.

All you need to know about single versus dual:

Single vs. Multiple +12V rails: The splitting of the +12V rail - jonnyGURU Forums

Quoting the "bottom line" from it:

The bottom line is, for 99% of the folks out there single vs. multiple +12V rails is a NON ISSUE. It's something that has been hyped up by marketing folks on BOTH SIDES of the fence. Too often we see mis-prioritized requests for PSU advice: Asking "what single +12V rail PSU should I get" when the person isn't even running SLI! Unless you're running a plethora of Peltiers in your machine, it should be a non-issue assuming that the PSU has all of the connectors your machine requires and there are no need for "splitters" (see Example 1 in the previous bullet point).

 

[ICIT2LOL]

Thanks ignazatsonic I was just curious as I have built power supplies for different purposes in the past and all have been "single rail".

My only "concern" was that if one of the twin rails went south then it would leave half the machine without power or worse catch fire. So a single rail would in fact make more sense in that eliminating problems is that much easier should the PSU be the fault

 

[ignatzatsonic]

Thanks ignazatsonic I was just curious as I have built power supplies for different purposes in the past and all have been "single rail".

My only "concern" was that if one of the twin rails went south then it would leave half the machine without power or worse catch fire. So a single rail would in fact make more sense in that eliminating problems is that much easier should the PSU be the fault

Hmmm.....how would that be worse than if the single rail went south, leaving all the machine without power and catching fire?

As the first sentence of the article says "In most cases, multiple +12V rails are actually just a single +12V source just split up into multiple +12V outputs each with a limited output capability."

And some "split" rail PSUs aren't actually split.

Single rail is less expensive to make, so there is more money for the manufacturer if the buyer can be convinced through marketing that single is preferable.

 

[ICIT2LOL]

Yep I get your point I was just thinking about those that are in fact two rectification units in one PSU and I suppose one could keep going back to the transformer/s itself / themselves and in that case they would probably be the prohibitively expensive ones - if my experience of building power supplies is anything to go by.

Transformers capable of putting out that sort of current always were very pricey and I am talking of even ones that would put out 15v+ at 5A from a particular voltage tapping / winding.

Most of my reason for the query too was that I am having to choose between buying a new single rail PSU and a used but in good condition twin rail Coolermaster I already have for a friend.

 

[ignatzatsonic]

Most of my reason for the query too was that I am having to choose between buying a new single rail PSU and a used but in good condition twin rail Coolermaster I already have for a friend.

Unless the friend had some very odd PSU requirement, I wouldn't agonize at all over the single/twin issue and would instead concentrate on comparing the Coolermaster against whatever new PSUs are in your price bracket and available from your suppliers. Build quality, age, price, warranty, reviews, etc. Coolermaster may or may not be near the top of the food chain.

 

[gazz9496]

quality of psu is the most important factor.

you can usually rely on the usual brands for decent quality, antec/coolermaster/thermaltake/corsair/seasonic/ocz i'm sure there are others.

power requirements, get more than you need. why? well you may be planning to update or upgrade your machine and assuming you bought a quality psu it will probably last for a while and if you bought a 750w where 550w would have been enough you have wiggle room for upgrades within your platform without having to shell out for yet another power supply.

never skimp on your power supply, if it seems to cheap chances are it probably is.

 

[ICIT2LOL]

quality of psu is the most important factor.

you can usually rely on the usual brands for decent quality, antec/coolermaster/thermaltake/corsair/seasonic/ocz i'm sure there are others.

power requirements, get more than you need. why? well you may be planning to update or upgrade your machine and assuming you bought a quality psu it will probably last for a while and if you bought a 750w where 550w would have been enough you have wiggle room for upgrades within your platform without having to shell out for yet another power supply.

never skimp on your power supply, if it seems to cheap chances are it probably is.

Yeah Gazz I was going to reply to ignazatsonic re this last night but was called away.

In all reality it does come down to quality and I might just get a 480W Corsair for the friend as he is into graphical stuff and I am now real sure the older Coolermaster I have as good as it appears may let him down.

So all up better going new I mean if the mains winding burns out in anything then it's not going to work however many rails one has on it.

But I have to say this has been a real learning experience all the same as my supply building was generally aimed at chargers and electroplating supplies.

Thanks for the time and patience of all

 

[Proximon]

I maintain a PSU guide at the TH forums, where I try not to get too technical. There are many of the same links and more as well. Also a glossary, and a link to a small list of PSUs often recommended.
Computer Power Supplies - A Guide - Power-Supplies-PC-Cases-Case-Mods - CPU-Components

Not that you can see it right now, forum is down temporarily

 

[ICIT2LOL]

I maintain a PSU guide at the TH forums, where I try not to get too technical. There are many of the same links and more as well. Also a glossary, and a link to a small list of PSUs often recommended.
Computer Power Supplies - A Guide - Power-Supplies-PC-Cases-Case-Mods - CPU-Components

Not that you can see it right now, forum is down temporarily

Hiyya and welcome Proximon that's a nice link you have added - and have saved it to favourites