If your computer refuses to boot or tends to turn off without warning, see the Faulty Power Supply to Motherboard problem page for possible causes and solutions.
The manual for your motherboard states that "You cannot use both 20-pin power connectors located at JWR1 (the right side connector) and JWR2 (the left side connector) as input power supply connectors at the same time. Only one connector can be used for input power supply to the motherboard at one time. For proper use of these proprietary PWR Connectors, please customize your PWR cables based on the Power Connector Pin-Out Definitions listed on Page 2-14". You can download the manual from here. Hope this helps, good luck.