Simple PSU question: max calculated need is about 780w, is an 850w enough or do we need 1000w?

[Elizabeth_33]

My friend wants to add a second GPU to his machine, and his power supply needs an upgrade. I used several different calculators on the web, and they have each given a requirement (assuming no overclocking, which he has no intention of doing) of about 780 watts. He would like to know if an 850w power supply is sufficient for this. I've seen people consistently go way over their power requirements on builds, and I'm wondering if there's a practical reason to do that, since there's a reasonably big price jump between the 850w and 1000w models of PSUs. As stated above, he has zero intention of ever overclocking the components, so ~780w is the absolute ceiling for his power requirements according to the Be Quiet! calculator.

 

[AppleGwava]

Those people either have large egos,large wallets or small brains,or are people with great ambitions.You dont need so much.

A 850 watt psu should be sufficient for him,most psu calculators already add a bit of headroom