What is the maximum power supply that I can just plug into the wall and not blow everything up?
I'm building my first system powered by 850W power supply.
Thanks for your help.
I needed that laugh.
850 is a pretty nice power supply with plenty of juice but there's no such thing as a maximum PSU you can get - you can have 2 2K watt PSUs and you'll still be fine, as was said the system will only draw what it needs.
You have a legitimate question, however overloading a circuit usually doesn't blow anything up. 850w is the max power output of the system can handle. At 80% efficiency, that means you could be pulling around 1060 watts from the wall at full load. Most modern power circuitry handles a maximum of 15 amps at 120 volts, or 1800 watts. That means that you shouldn't put more than 740 watts of other equipment on the same circuit. This doesn't just mean one outlet, multiple outlets in a room can be tied to the same circuit.
You should be completely fine using any size psu as long as you don't overload that 15 amp GFI with other equipment.