Look up the specs for the card you want to buy, it will tell you. Sometimes card companies add more power than a stock or reference one because of more fans, it's overclcocked, etc, so it's best to lookup the actual card you want to buy.
If the cx600 is enough for 1 * R9 270x what PSU would you suggest for 2 of them in crossfire. Obviously need 4 * 6 pin plugs or what would be the best other plugs to adapt to 6 pin. HELP!!!