ATX PSU's

[Crypticalcode0]

Okay the white cord is minus 5 Volt but why is this voltage required for?
I am aware that older CPU needed this voltage but this is a archaic practice. even back in the early 90's

More modern ATX PSU have dropt this but the older one's have this 'feature' still.

 

[keropi]

The -5v line goes to the ISA bus and is needed for some older isa cards, most notably the ROLAND LAPC-I and some of the first 8-bit SoundBlasters ... If you have none of these cards then you can use a psu that lacks the -5v line.