Eli5 techy: online calculator recommends 400W of power supply, but VGA recommends 650W, is there a problem going below recommended?

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I’m about to upgrade my desktop computer. Using an online calculator and adding my components, it recommends a bit more than 200W of power. When I replace the VGA with the one that I want, it recommends 400W power. But when checking the VGA alone, it’s store page says: power supply 650W or more recommended.

My question is, I already have a 450W power supply, can I go with it? And what happens if the power is not enough? Will I risk any component?

Obs: Perhaps the calculator specifies raw energy, while the power supplies can deliver like 80% of what they say?

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15 Answers

Anonymous 0 Comments

Many power supplies can’t live up to their ratings

This was a big problem where power supplies would say 650W but 200W were available on the 5V rail and only 450W on the 12V but 99% of the power a computer draws these days is from the 12V rail. A good 450W power supply will be able to supply 37A on the 12V rail but a common one won’t

Go to /r/BuildAPC to check your exact specs but in general you don’t want to plan on running your components at 100% of their ratings. It ages them faster and a power supply’s capabilities drop as it ages and it’s capacitors don’t hold as much

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