this post was submitted on 07 Jan 2025
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1000W PSU pulls max 8.3A on a 120v circuit.
Residential circuits in USA are 15-20A, very rarely are they 10 but I've seen some super old ones or split 20A breakers in the wild.
A single duplex outlet must be rated to the same amperage as the breaker in order to be code, so with a 5090 PC you're around half capacity of what you'd normally find, worst case. Nice big monitors take about an amp each, and other peripherals are negligible.
You could easily pop a breaker if you've got a bunch of other stuff on the same circuit, but that's true for anything.
I think the power draw on a 5090 is crazy, crazy high don't get me wrong, but let's be reasonable here - electricity costs yes, but we're not getting close to the limits of a circuit/receptacle (yet).
Actually the National Electric Code (NEC) limits loads for 15 Aac receptacles to 12 Aac, and for 20 Aac receptacles 16 Aac iirc because those are the breaker ratings and you size those at 125% of the load (conversely, 1/125% = 80% where loads should be 80% of the break ratings).
So with a 15 Aac outlet and a 1000 Wac load at minimum 95% power factor, you're drawing 8.8 Aac which is ~73% of the capacity of the outlet (8.8/12). For a 20 Aac outlet, 8.8 Aac is ~55%% capacity (8.8/16).
Nonetheless, you're totally right. We're not approaching the limit of the technology unlike electric car chargers.
The NEC limits CONTINUOUS loads to 80%, not intermittent loads. Continuous loads are things like heaters, AC units, etc. Things plugged into the wall are generally not considered continuous loads, so your breakers in a residential home are usually not derated, and receptacles never are from what I've seen. (Although it could be argued that a gaming computer would be a continuous load, as it runs 3+ hours for many people, but there's still no electrician that would treat it that way, probably ever, unless it was some kind of commercial space that rented gaming seats or something. Either way it would be planned in advance)
The rule that you're describing is for the initial planning of the circuit. It's for the rating of your wires and overcurrent protections, which is done at the time of installation, based on the expected continuous and intermittent loads. For residential planning nobody treats a standard branch circuit for wall receptacles as somewhere you'd derate, so your 15A circuit is a 15A circuit, you don't need to do any more math on it and derate it further.
You could make the argument that people with 5090s do run their PCs longer than 3 hours since those folk are more prone to longer bouts of gaming to feel like they're returning on their expensive investment. And as the capabilities of our PCs become more and more robust, it will likely mean that people will more and more need to consider whether the circuit they're plugging into will take the load they're giving it.
Doesn't hurt to plan for the future regarding building wiring, since most tech folk do so regarding their PC builds.
But, up on further inspection... I may be inclined to agree with you. See this thread from licensed and qualified professionals in the space.
It seems that homeowners are given a special class of immunity when it comes to manifesting hazards associated with their use of electricity. Whether or not that immunity should be granted, given that improper use of electrical equipment in a household can lead to fires and cause undue harm to the community at large, I think is up for debate.
That's just the GPU with efficient other parts. Now if we do 575W GPU + 350W CPU + 75W RGB fans + 200W monitors + 20% buffer, we are at 1440W, or 12A. Now we're close to popping a breaker.
This makes me curious: What is the cheapest way to get a breaker that can handle more power? It seems like all the ways I can think of would be many 5090s in cost.
350W CPU?? Even a 14900k is only 250W, most are 120-180.
75W of fans????
I'm sure you could find parts with that much draw, but that is not normal.
How many RGB fans does this theoretical build have to use 75W alone?
How else are you gonna cool 925W in a PC form factor? Ever seen fans for server racks?
hire an electrician (or dependent on local laws DIY) to add a dedicated 240v 20a outlet with 12/2 wire.
Out of curiosity, how much does this cost with an electrician?
How far out are we from gpus that also dry your laundry