Trying to benchmark, computer restarts, Ubuntu 14.04

[alphAEcho]

You roughly need 400W for powering each card alone. That's without the other system components. Also your power supply should not have more than 85% utilization in total.

I understand, i have this power supply http://www.lepatek.com/eng/product_content/1/1/20/

I'll remove two of the Graphic Cards, just to see how it works.

Thank you for the information, this was very helpful.