I have never seen a DC power outlet jack on the rear of a PC (Home Computer). Can you post a picture? Explain in detail exactly what this jack looks like? This jack is actually on the PSU? How about can you provide the make & model of the computer? That may help. This is a desktop correct? You are not talking about the power in (jack) connector on a laptop would you?
If it is a female DC Barrel jack (may be purple) it is 12V from the PSU to power speakers. I am not sure if it is regulated and have not personally measured it with a multimeter. I guess it is regulated though. I have one on my back of my PSU case and one on my monitor
Yes 3lectrokid, It is the female barrel type, I have a custom device that a customer needs repaired and he use to connect it to that power jack. Thus I dont have access to thejack to measure it. Thanks!