RADEON 7770 PROBLEM

Hello i just bought an AMD RADEON 7770 1gb, it's the MSI version. And it doesn't work on my computer, the monitor just wont recognize it, it says no signal on the display. But the graphic card works fine on my friends computer. So I have a 400w psu, and he has a 450w , i tried both of them and both didn't work on my computer. So it's not the PSU. I also tried with a dvi and hdmi cabel, didn't work again. My motherboard is ASRock N68PV-GS, and it supports the radeon 7770. Then I also tried my friends graphic card to put in my computer and it works fine. His graphic card is RX 550 and it works great on my PC, but the much older 7770 doesn't. So can you please help me, what can i do ?
My computer components are:
ASRock N68PV-GS
AMD ATHLON ii 640 3.0 quad core
WINDOWS 10
Chipset NVIDA nForce 7xxx-6xx, AMD K10




4GB RAM DDR2