Help with power cycling!

I have an Alienware Area – 51 ALX that is cycling power, but wont boot to bios.

I plug it in an turn it on, the fans turn on, the fins go through the normal start up cycle, but then they cut off, and it goes in a 6 second loop (3 seconds on, 3 seconds off) there obviously is power getting to the motherboard and the power supply tested fine. Here is what I have tried so far.

- Replaced RAM

- Replaced HDD

- Reset CMOS

- Unplugged all non essential items (DVD, Front panel USB's, etc)

Any help would be greatly appreciated. Thank you.

*** EDIT *** I tried draining the power by unplugging it and holding the power button for 10 seconds and it booted up without a problem, thanks to anyone who was thinking about responding!

***RE-EDIT*** It was working for 5 minutes and it shut off and started cycling power again... HELP!