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PSU Compatibility - First Build Question

apolk27
  • 60 months ago

Hi, was wondering if PSU & GPU compatibility is only dependent on the wattage? Planning a build after the 390/980ti release & would like to buy as much as possible beforehand to take advantage of any good deals that pop up over the new few months.

Also, is it okay to buy a PSU with a much higher wattage than is required? I have to export everything out of the U.S. (big hassle) so it'd be nice if this PSU would last a long time.

Thinking about an EVGA 220-P2-1200-X1 (go higher just to be safe?)

thanks for the help!

Comments

  • 60 months ago
  • 1 point

You can use a psu with a much higher wattage than you need, it just might not reach its stated efficiency.

  • 60 months ago
  • 1 point

thanks

  • 60 months ago
  • 1 point

When choosing a PSU I tend to look at the total wattage as well as the max. current on the 12V rail(s) and the branding.

Next to the total wattage you might need to check how much the 12V rail can provide since this is the source where most of your components (mobo, GPU, disks) will draw their power from. Next to the total wattage, make sure that the maximum current (in Amps) that the 12V rail can support all your devices (or that nearly all power can come from this rail). For high tier units this is usually the case. For the PSU you've selected, you can see that it can provide 99.9A (at 12V = 1198.8W) so that's good.

With regards to over provisioning, you need to think about the expected load your system will need. Most PSUs operate the most efficient when loaded for about 50% to 80%. Going higher, efficiency decreases a bit, going lower the same. Now, your EVGA has a 80 Plus Platinum rating, which means it has an efficiency of 90% or more for loads between 20% and 100%. Below 20% (or 240W in your case) there is no guarantee for the efficiency. So you might want to consider going a bit lower, for instance towards a 860W or 1000W PSU, depending on your plans. What's difficult in your case is that we don't know the cards power draw, certainly in the case of the 390. For one GPU 860W should be ample in any case, but there's a small risk of needing to upgrade if you want to go with multiple GPUs later on.

As for branding, EVGA is a great choice. Other great PSU brands are, for instance, Corsair AX series and Seasonic.

TL;DR: Looks like a great choice, but I'm not sure you'll ever need that much power (depending on your hardware plans of course) which might reduce efficiency a bit.

  • 60 months ago
  • 1 point

Thanks for taking the time to share your knowledge, really appreciate it.

Went back & looked at the output of 12V rail on different models to gain a better understanding of what you said. Was a bit confused at first but makes perfect sense now.

Definitely planning on an SLI/CF setup or I'd take your advice & go lower.

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