Note: I'm answering your post with the assumption that you plan on using this power supply with a computer. If this is not your intention, please disregard my solution attempt.
You likely already know this, but if you are powering a computer you're going to need a power supply with more wattage. I would recommend nothing less than a 350 watt power supply.
Follow this link to calculate how much power you need to run your computer: http://www.extreme.outervision.com/psucalculatorlite.jsp
If you're not ready to give up on your 270 watt power supply, then remove all PCI/PCI-E devices, USB ports, extra fans, non-boot hard drives, extra DVD/CD drives etc. one at a time until the computer powers up. Anything you can do to reduce the load on the power supply will help.
Good luck and thanks for using FixYa.