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Power Supply Calculators are Inconsistent

TyeEye

24 months ago

I put my system info into 5 different calculators but they aren't very helpful. Here is what they put out:

Newegg- 515 watts Outervison- 400 watts PcPartPicker- 300 watts Seasonic- 400 watts Be quiet- 300 watts

What power supply will I need?

Edit: Here is my build, I'm not sure how to properly export it into the post but it's here anyway: https://pcpartpicker.com/list/WdrJjc

Comments

  • 24 months ago
  • 1 point

System specs?

  • 24 months ago
  • 1 point

Despite their ironic name they aren't accurate. Especially ones from retailers or brands since it is in their best interest to sell you the most expensive PSU possible. PCPP never under estimates but it often over estimates.

What is your build.

  • 24 months ago
  • 1 point

450-550 watt ranges tend to be fine for the vast majority of builds. So, if you post your build list we could give you a decent estimate. But, it will likely fall around this range. I can take a guess based off of the estimates you got from those sites though and say that since PCPP recommend 400, a 450 watt PSU will definitely suffice. This kind of lines up with Vagabond's assertion (which is correct) that PCPP won't underestimate the needs, but will often over estimate them (for good measure).

  • 24 months ago
  • -1 points

According to EVGA's requirements for the graphics card that you selected they recommend:
"400 Watt or greater power supply"

  • 24 months ago
  • 1 point

EVGA does that because they have to account for a variety of systems with a variety of different PSU's. His build would be lucky to use more than ~230W.

  • 24 months ago
  • 1 point

Uh huh I see...
Does this mean that all graphics cards manufacturer overestimates?

If so how could you tell what amount of power you would need at a minimum for a computer build?

  • 24 months ago
  • 1 point

For a non insane (i.e not threadripper, FX 9590, i9, no 20 delta fans, no running a toaster off molex, etc) and for a build with a PSU worth its salt (i.e not a Logsyis PSU) they all pretty much over estimate.

The best way to figure out roughly what a build will use is to look at real world power usage from reviews and calculate what the system itself is using since they will all list power draw from the way. Then you will need to do some digging around and comparisons to get a idea of what X will since if they are using Y CPU. Although sites like Anandtech always use a extreme power hungry i7 so if you are running a Coffelake/Kabylake or a Ryzen CPU you can just subtract like 30W or so for a rough idea.

For example.

https://www.anandtech.com/show/10540/the-geforce-gtx-1060-founders-edition-asus-strix-review/16

The highest draw was 279W. That is from the wall so we need to account for efficiency. We do this by figuring out what the effiency of the PSU is. I assume its gold and at .9 since its nice round number. You will then want to multiply by it. 279W * .9 = ~250W that is roughly using here and subtract like 30W to account for the power hungry CPU and it comes out to be roughly 220W which comes out close to what I said above. Its not a perfect way to figure out power usage but its good enough. Keep in mind though this doesn't mean you should go out and buy the smallest PSU possible.

  • 24 months ago
  • 1 point

huh not sure why people downvoted this comment but if I said anything wrong or stupid please let me know

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