PSU wattage calculations for new build

Benjamin_20

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Feb 2, 2016
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I'm currently pricing up a new build. I was thinking about doing 1950x + 2x 1080 ti on a full custom loop. I checked some reviews and an overclocked 1080 ti can at max load pull just over 300w same thing with an OC threadripper. So ballpark potential of 900-1000w power consumption just between those parts + pumps, fans, overhead etc looks like a shit load of power consumption.

Currently have a corsair AX850 which doesn't look like it's going to be enough, is a 1200w power supply a reasonable solution as real world consumption won't be peak consumption all the time or does a build like this require a 1500w PSU?

This build is a my first run in HEDT I'm used to building much more efficient rigs with far smaller PSU's. I used a psu calculator that estimated 1050w power consumption which looks like the 1200w would be enough for. I remember reading sometime ago that it's better to have a power supply only just over the actual draw and not ridiculously over the top as it's less efficient not sure if that's actually true.
 
Solution
You said it yourself. 300+300+300=900W. I would then add 50W for a typical rest of the system, and then add whatever your pump uses. You could be looking at ~1kW. That's also before OCing the GPU if you want to, though I don't think that will add much more seeing the TIs are already OC'd quite a bit to hit 300W. You want this 1kW number to be no more than 80% of what the PSU can output on it's 12V rail(s). This means you need something that outputs AT LEAST 1250W. In this case, I would pick a 1.5kW PSU. A really good 1200W can do it, but you'll stress it above 80% output while stressing it and that's not good for the life the PSU.

4745454b

Titan
Moderator
You said it yourself. 300+300+300=900W. I would then add 50W for a typical rest of the system, and then add whatever your pump uses. You could be looking at ~1kW. That's also before OCing the GPU if you want to, though I don't think that will add much more seeing the TIs are already OC'd quite a bit to hit 300W. You want this 1kW number to be no more than 80% of what the PSU can output on it's 12V rail(s). This means you need something that outputs AT LEAST 1250W. In this case, I would pick a 1.5kW PSU. A really good 1200W can do it, but you'll stress it above 80% output while stressing it and that's not good for the life the PSU.
 
Solution