ASUS P9x79 PRO having problems with my PSU

[uromastix87]

I've been using my homebuilt PC for a few years now and decided to upgrade. I get a new mobo, CPU, GPU, HSF,and PSU. Hook it all up in my old case and old HDDs. When I power it on it will come on for a split second with the CPU_LED on and red then shuts off. A second later it comes back on and repeats 'till I cut the power. I looked it up and it looked like a bunch of people were having the same problem with the same mobo so I RMA the mobo. While I'm waiting for the rma I set my old PC up WITH my new PSU and it runs fine.
New mobo comes back I hook everything up but since my old computer is using my new PSU I use the old PSU. It runs fine. But when I put the new PSU in I get the same problem as before.

NEW PC SPECS:
PSU: http://www.newegg.com/Product/Product.aspx?Item=N82E16817153145
CPU: http://www.newegg.com/Product/Product.aspx?Item=N82E16819116492
RAM: http://www.newegg.com/Product/Product.aspx?Item=N82E16820231638
GPU: http://www.newegg.com/Product/Product.aspx?Item=N82E16814130785

NOTE: The red CPU_LED probably means nothing seeing as how when it starts up normally it flashes anyways along with the other leds.

Thanks for your time and help in advance. I'd really like to get this PSU working with this build because I was thinking of getting another gpu and the old PSU doesn't seem reliable.

 

[clutchc]

If you're trying to boot to Windows from the old HDD with the old Windows installation on it, I'm not surprised it won't boot. Windows needs to install from the MB it will be used on. Do a fresh install.

Btw, if your copy of Windows is an OEM, you may have to jump thru a few hoops when you try to activate it after a fresh install. OEMs are licensed to the MB it is originally installed on.