How many GPU's on a power supply

I would like to know how many GPU’s can I fit on a 750w power supply. I am still running 1 PNY XLR8 1660 and 1 PNY XLR* 1550 Super GPU’s on my gaming computer as I have not built a rig yet, and I would like to add a 3rd 1660 Super GPU. Can I run 3 GPU’s and my computer safely with a 750w power supply? Also, I have someone who is giving me an AMD Radeon HD7850 2gb for free. Can I run AMD and the 1660s on the same motherboard? Thanks!

First I think you will be okay with the 750W psu I am guessing your NVIDIA cards are using around 120 watts each. I had a rig with NVIDIA and AMD cards on the same rig but it was not easy and it was not stable when I did get it to work. I do not think you will want to add that AMD card to your rig and it wont do much good on its own.

If you do not know for sure assume your motherboard is using around 150 watts then you have 3 cards using 120 watts so that is 360+150=510 watts which is less than 80% of 750 watts.

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I’d recommend picking up a wattmeter if running on standard (US) 110v outlet, usually around $10-15, plugs into outlet and plug PC into it, lets you know the total power draw of your rig. Ideally you don’t want to go over 70% or so usage to maintain the efficiency, depending upon the rating (Gold, Platinum, titanium) of the psu and wether you are on 110 or 220v.

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WhatToMine has the watt usage for cards on their GPU breakdown, at least for the main cards used for mining -

still a good idea to know your total usage from the wall you could have an unknown issue and be drawing more than you should be and that also doesn’t account for your MOBO and CPU and Risers and case fans if you have any