Need help! New pc build won't boot correctly.

[stumperd]

Hello,

I decided to upgrade my graphics card because it really sucks. So I bought the Asus HD Radeon 7870 DirectCU II graphics card.
After I put the graphics card in my pc, and I'm pretty sure I did it correctly, my pc does boot but my monitor says: No video input
So I tried using a HDMI cable instead of a DVI cable but still, it wouldn't work. Although the monitor says no video input, the fans on the graphics card were working.
So i figured I probably should buy a better PSU since I had a 450W PSU.. So I bought a 650W PSU and a better case with better ventilation and more space.
But it still wasn't working.. Exact same problem.. I have no idea what do to now.

So can anyone please tell me what the problem is and what I should to do make it work?

My specs are:

OS: MS Windows 7 Home Premium 64-bit
Processor: Intel Core i7 2600 @ 3.40GHz
RAM: 6,00 GB Dual-Kanaal DDR3
Motherboard: MEDIONPC MS-7728
Graphics card: ASUS HD Radeon 7870 DirectCU II (ATM I have AMD Radeon HD 6570)
PSU: OCZ ZS Series 650W
Hard disk: 977GB Seagate ST31000528AS ATA Device (SATA)
Case: Zalman Z11 Plus
Monitor: Philips 244E (1920x1080@60Hz)

Thanks!

 

[Joe C]

That card needs 2x6 pin pcie rails for power to it. Did you connect those?

 

[stumperd]

THANK YOU SO MUCH! I only connected 1x6 pin pcie rails, the box said 1 was enough. Apparently not But it's working now! thanks!