I am trying to power some raspberry pi's with a powersuply from a old HP proliant g4 server I recently stripped. I know it is possible on a standard powersuply to short pin 4 to ground (I think it was the green one) and turn the psu on. There is no green pin 4 on the small 20pin port or the big 16pin port... Does anyone know how to turn the powersuply on without the motherboard?

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