Positive usually has a small mark on the connector. Look for an arrow or other marking.
For power switches it makes no difference unless they have lights on them (or any other electrical function other than to switch on the PC).
What is ransomware and how do I protect my PC from WannaCry?
Disney layout supervisor Rob Dressel on the challenges of visualising Moana
Siri vs Google Assistant
Synology invites you to visit them at Insomnia on 26th – 29th August. Book your tickets now and visit Synology.