Can I get 24 V from ATX PSU using 12 V and -12 V cables?

Question

ATX PSU's have one -12 V cable, and a few 12 V yellow ones. Could I power up a 24 V device by connecting 12 V to + on the device and -12 V on -?

Answer 1

It depends on the device. You get 24 V but the -12 V is usually low power. So you could get a reference voltage. You could use it for powering very low power devices. Check the current rating of the -12 V line on your PSU.

If you want to use your ATX PSU to get 24 V, you should get a DC-DC boost converter from 12 V to 24 V. They are cheap and powerful.

Answer 2

Yes, but be aware that you are essentially redefining ground for your 24V supply to be 12 volts lower than the ground for the other power supply outputs (5V, 3.3V). This may also be true regarding the neutral and protective ground of the AC input. You will need to be extremely careful if you make an electrical connection between your 24V device and any other electrical device or to earth ground. If you just want to run a small 24V fan you would probably be OK, for example.