New system won't boot

[Captk]

I just put together a new system, AMD Phenom 720 X3 on a Gigabyte MA790X-UD4P mother board. I put the 20+4 power supply in but where I would expect a 4 pin power supply there is an 8 pin. The connector is listed as ATX_12V_2X4. I don't want to take a chance and mess up the board so I am seeking help. Do I need to get another adapter for a 4 pin to 8 pin power connector? The manual is lacking is description. When I booted the system the monitor doesn't register a connection and display "Error No Signal".
When I turn the system on the DVD get's power and I can see the fan spinning on the video card and a red light is on. Both the motherboard and video card had bare installion instructions. I did connect the 6 pin pcie power connector to the video card and it's tight in the slot. I have a Sapphire 4830 video card, WD 320 GB HD. Pretty straight forward system, nothing fancy.
Thanks in advance, Ken

Never mind, I found I need to get a 4 pin to 8 pin power cable adapter.

 

[DAPUNISHER]

I am not familiar with that board, but did you plug in the 20+4 to fill all 24 pins of the ATX connector? Because the manual states

Do not insert the power supply cable into pins under the protective covers when using a power supply providing a 2x2 12V and a 2x10 power connector.

 

[Captk]

There were no protective covers on the 24 pin connection. anyone have any experience with this MB?

Ken

 

[DAPUNISHER]

You misunderstood my post, you should be plugging in your 20+4 ATX to all 24 pins. Protective covers would have been over the 8 pin connector, of which pins 3,4,7, and 8 (the top 4) are for ATX 2x2 4 pin 12v.