Question 1

Is it a problem that AT systems need a -5V rail (white wire), but modern ATX power supplies do not have -5V?

Accepted Answer

Unless the board is real old (like an original IBM PC or AT), it probably won't need the -5 V rail. Power supplies have not supported -5 V for some time.

I bought this cable with a Coolmax A-300 P.S. to replace the original AT supply used on a 15 year old lighting control console. The -5 was not used in this instance.

Question 2

where do I connect the green and black wires to?

Accepted Answer

It depends on what you are connecting this to. If its for an older at machine, they would go to the switch. These two wires are technically the power on wires. If you just connect them directly together it will come on, but they will have to stay connected for the power supply to stay on. The switch in an AT computer was a push on/ push off switch. You can use a toggle switch or even a household light switch if you just need something to turn it on and off.

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