PCA Forums

what is the -5v part of the ps do anyway? what does it run?

Some electronics require it. Memory used to require it, but not sure if that applies to modern memory anymore.

I know -12volt is used by serial ports.

thank you Mr Flying Penguin, that explains why the "dead" power supply with the non functional -5v rail is powering my old p 133 with no trouble at all.

Not suprising. I think old 72 pin simms from the 486 era used them, and there may be some cards that use them, but more an more everything is standardized for +5 and +12Volts now. Makes it easier to design laptops that way as well.