Put Together new Build - Starts for a second, then off and repeats

As stated in the title, I just put together my computer with all new parts, case and everything. After connecting everything and excitedly finalizing all connections I pressed the power button and the whole thing will light up and everything starts spinning, but lasts a second. Then it turns off, and goes on to try again on itself repeatedly, in a cycle fashion until I shut my PSU off manually.

I actually took a very short video of this:
http://www.youtube.com/watch?v=7nLsEAbwP5k&feature=chan... (mb, Phantom Planet appears to be blaring in the background, even though it wasn't)

Alright, let me give the specs:
i5 Quad Core CPU
ASUS P7P55D LE Motherboard
G.Skill Ripjaws DDR3 RAM (4x2048MB) - F3-16000CL9D-4GBRH - http://www.gskill.com/products.php?index=227
Thermaltake SpinQ - CL-P0466 CPU Cooler
SAPPHIRE 100269OCSR Radeon HD 4890 1GB 256-bit GDDR5 GPU
OCZ GameXStream 850-Watt Power Supply
Western Digital Caviar Green 1TB Hard Drive
No OS Yet - Waiting on Windows 7 OEM to arrive
NZXT Tempest ATX Mid-Tower Case
I just have a DVD Burner (internal) and that's everything.

I only have one set of dual-channel memory installed right now (in the correct spots according to the motherboard manual)

Concerns of mine, or problems I am thinking it is:
1) The power supply isn't strong enough, or I am overloading it in a certain area.
2) The memory (RAM) isn't compatible
3) I don't need an OS to get my computer spinning right? Sounds dumb but I need to exclude every possibility
4) The GPU is an open-box purchase, but appears to be in great shape and spins and everything when I start it up so I don't think that has a problem.

Steps I took to try and resolve the issue:
1)I tried re-setting the CPU and CPU fan with new thermal grease as I thought I had to much on there, but same result.
2)I tried changing the Molex connections around and using less fans from the case

This is my first total build with all this new technology, I've only dabbled before and been successful in the past. Really stumped here, I appreciate any and all help!