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by gothroach
2292 days ago
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>Outside of drives and fans, the virtually all of the power used in your system is exclusively 12v; either from the 12v pins on your ATX24 or P4 or EPS12 connectors, or via the PCI-E connectors; very little non-drive or non-fan power is supplied via 3.3 or 5v rails. I'm curious which fans don't use 12v - all the fans I know of in a typical computer operate on 12v except perhaps GPU fans. Occasionally I'll run a fan on 5v if I need it to be quieter and I don't have any PWM headers available, but that's about it. |
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Some systems control fans via voltage (the old way of doing it), instead of modern PWM (which has been the standard for about a decade); and even with PWM, it should be viewed as an average of the voltage instead of merely as the peak voltage during pulses.
No matter how you end up controlling your fans, you're not giving them straight unfettered 12v, either you're controlling them via voltage (and they spend most of their time at around 5-7v), or you're controlling them via PWM (with a significantly reduced load cycle).
Some ultralight laptops have switched to 5v for their fans, but that does not seem to be any sort of standard. I have not seen a GPU that uses 5v for fans, and by the time GPUs needed big enough fans to have to control the speed on, they were exclusively PWM, and I am not aware of a GPU that used voltage control on it's fan.