HELP - Board or PSU Issue?

I received 2 MSI Lightning R9-290x cards for a gift to replace my single 7970 MSI Lightning card. The new R9-290x no longer uses the cable adapter to do cross over and they new use the PCIe bus for cross over. I powered up the system with the first card and the system came up. Then I added the second card, now the system just "turn off then on" for one second repeatedly. I tried a second psu and it did the same thing.



I placed the original video card in and the error continues. I pulled out all memory, video cards and disconnected all SATA drives. The error continues with the "turn on/turn off". When the system turns on for the 1 second, power is provided briefly to the external USB drives.



I checked pcpartspicker and added the power requirements. I thought the RM850 was enough to power my system. The only solution I believe is my board (ugh) but does anybody have an opinion?



My question is, is this a board and/or PSU (not enough power)?



My systems spec are as follows:



Case: Cooler Master HAF 932 Full Tower

Memory: 32 Gb of Corsair Vengence

Board: Gigabyte GA-X79-UP4 Max memory 64 Gb

Processor: i7-3820

Video: (2) MSI R9-290x Lightning card

HD: 7 Western Digital 2 TB Drives

Optical Drive: Asus Bluray DVD writer

Operating System: Windows 7 Ultimate SP1 64 bit

USB connectivity: 6 external Western Digital drives, mouse, keyboard, HOTAS petals/rudder and joystick setup

Monitor: 48" Vizio LED TV