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What should I know to select a power supply?

What should I know to select a power supply?

I am planning to build a computer in the next year. What should I know about power supplies before I buy one? I'm putting together a check-list, so nothing is too simple!

Asked by: Guest | Views: 235
Total answers/comments: 3
Guest [Entry]

"http://www.firingsquad.com/guides/power_supply/
http://forums.techarena.in/guides-tutorials/1093105.htm
Here are a few guides to help you understand better.

Get a decent estimate of what your computer power requirements are because you want a power supply with a higher wattage rating then your needs.
Make sure to get the most efficient power supply you can afford. One with greater then 80% efficiency. This will save you on your power bill and your power supply will produce less heat.
You want a power supply with a min wattage rating at least 20% higher than your actual need.
Make sure the power supply you purchase has all the connectors you will need. If you are running SLI (dual video cards) or have many hard drives, you will need to make sure you will be able to hook it all up. Also consider future expansion options.
Not all 500watt (or any rating) ps are the same. (efficiency, rails, and fan noise can vary greatly)
Make sure the rails of the power supply can power your graphics card min. amperage needs.
Keep in mind if you want a quiet computer to look at the sound level ratings of the fans. They even make silent power supplies with large heat sinks and no fans for those who want total silence.
Try not to cheap out on the power supply if you build a relatively expensive computer. It is one of the most ignored components of new system builds. You want good clean power.
Another reason to buy a larger one would if you plan to upgrade the machine significantly later on.

Here are some reviews of power supplies available. Newegg.com is also a great place to look.
http://enthusiast.hardocp.com/reviews/psu_power_supplies/
Other good points brought up by other users:
@GalacticCowboy Motherboard/PS compatibility, definantly read about a motherboard purchase to make sure this will not be an issue.
@hanleyp Weight can be a rough estimate on a quality vs lower quality power supply. More weight commonly can possibly mean better beefier components and heat distribution."
Guest [Entry]

"Having a watt rating much higher than what you actually need is not desirable, because efficiency get much worse when you're operating below capacity. i.e. if you need 250W and buy a 500W unit then it may well operate at 60% efficiency even though it's declared to be 90%. And remember: more power used (or wasted) does not only mean a higher electricity bill, but also more heat, which in turn means more noise.

Most systems are never significantly upgraded, so you should buy a power unit that supplies just a bit more than your maximum need."
Guest [Entry]

"Please don't fall into the trap of slapping a 1200W PSU into a machine because it ""might need it"". You'd be surprised what a quality (Corsair, SeaSonic, newer Antec) power supply can actually handle. Add up the TDP's of your components. They won't draw more wattage than heat they can produce.

I've gotten a Thuban X6 1100T, with an overclocked GTX 550Ti happily running on a 400W Cooler Master power supply (peak draw linpack + furmark is 395W!). All the power supply calculators online said I needed at least 650W for that machine, but the PSU is rated 100k hours MTBF @ 100% load, so why not? Reviews said it had great ripple control at full load, and it's quiet.

I've got an a 650W Antec PSU running an overclocked i7-2600K with an overclocked GTX580, with plenty of headroom left over. Hundreds of watts left over."