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How much extra wattage should a PSU have?

DWW256
  • 61 months ago

Hello, I'm setting up a build that takes ~475W of power, and I'm wondering if there will be any issues if I give it a 500W power supply. I wonder this because I look at other power supplies on 400+W builds, and they have 750+W power supplies! Is there something wrong with only leaving 25W left over, or am I just crazy?

Comments

  • 61 months ago
  • 4 points

There is a "sweet spot" in PSUs vs calculated system demand, where the PSU supplys enough ready power but never quite exceeds its rating on any one output, and so it lasts, generally, the entire lifecycle of the system it's mounted in.

Rule of thumb for us old guys (50+) is between 25% and up to 40% above expected system requirements.This is just cheap insurance we've learned, since trouble-shooting a system down to where you can be sure the PSU is faulty is not a bit of fun, even if you are pretty good with decent multimeter.

A hosed up PSU can cause ANY part of your system to act crazy, and even never twice the same way the same day - so you get to try to chase down bogeys involving multiple software, firmware and hardware at the same time - Now that sounds fun doesn't it?

Basically, buy a damned good PSU, and get one between 25% and 40% more than you think your system might require. The added benefit to this "inefficiency" is that your PSU capacitors and such will last LONGER, because they are never stressed to their max.

  • 61 months ago
  • 1 point

base on your graphics card, this list should give you an idea of what you need, this are minimum requirements.

http://www.realhardtechx.com/index_archivos/Page362.htm

many ppl buy more powerful PSU as some are planning on SLI or crossfire.

  • 61 months ago
  • 1 point

Not all psu deliver there rated wattage. A 500w psu might only give 480w leaving you with no room. Also,running a psu near max full time will kill it quickly. If you ever choose to overclock your cpu and/or gpu, that can easily add 100w to your system draw. At which point you would be trying to draw 575w from a 500w psu.

  • 61 months ago
  • 1 point

My rule of thumb, for me, is to get a PSU that is 1.5 to 2 times more than your rated wattage. So if your at 480 I'd get a 750 or higher PSU. That way you are never overtaxing the PSU. Which, as stated above, is bad for a PSU.

  • 61 months ago
  • 1 point

For ~475 W of power supply 650 watts is more than enough.

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