Video Card Or Mobo?

I had a problem where I turn on my computer and got no video ... I could here sound, but no video ... so I figure it was the video card. I hooked up the monitor to the mobo and got video. We had a brief power loss, and the computer shut down. A few hours later I boot it up and no video with the monitor hooked up still to the mobo video. The video card was still hooked up to the mobo. I hooked the monitor back into the video card and I got video again. Any ideas what the problem is? So far I'm still getting video from the card. This is my AMD FX computer that is in my sig.

 

I replaced my old video card with a new one ... the ZOTAC GeForce GTX 550TI. When I tried to install the latest driver and reboot the computer I would get a blue screen. So I had to go back to the driver that is installed. I went to Zotac's download site https://www.zotac.com/us/files/download/by_product?p_nid=334064&driver_type=235&os=245 there are two other drivers besides the one I tried to install for my OS. But which one? Now when I boot up the computer I get this error message ... "main message window:NvBackend.exe - Entry Point Not Found ... The procedure entry point InitializeCriticalSectionEx could not be located in the dymamic link library KERNEL32.dll." What do I need to do to correct this?