Specifically graphics cards. How do we come to the conclusion that the official PSU requirement for a GPU by the manufacturer is higher than what it actually needs? If a GPU is meant to be 340W, is that always the case or only when it’s really number crunching when a game is modern and is set to ultra settings?
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If we look at [https://en.wikipedia.org/wiki/Thermal_design_power](https://en.wikipedia.org/wiki/Thermal_design_power)
>The thermal design power (TDP), sometimes called thermal design point, is the maximum amount of heat generated by a computer chip or component (often a CPU, GPU or system on a chip) that the cooling system in a computer is designed to dissipate under any workload.
So it is the max power the cooling system can handle. It is not necessarily the max power the GPU can draw. For a short period of time, it can use more power but it results in an increased temperature. It will be the max power that on average can draw over time.
The reason you need a PSU with a higher rating is that there is other components in the computer that use power too. The max power usage can be shorter for small periods of time.
PSU alos exits in single and multi-rails variants. With multi-rail, the max power can be split-ups so the connection to the GPU might not be able to supply all of the power,
The efficiency of a power supply depends on the load on it. So a PSU with large max power can draw less energy out of the wall outlet than one with a smaller max power. You can see 850W power supply is most efficient at around 300W https://www.techpowerup.com/review/corsair-rmx-series-850-w-2021/5.html
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