Do you have the manual? I am uncertain as to what they specify as "Video Cable".
The G6-350 is no longer listed at Gateway's site although they have this generic page:
http://support.gateway.com/support/m.../desktop.shtml
Scroll down under Installation Guides: Then:
Memory Installation Guide. That is RAM. I would remove & then replace (re-seat).
Also look at:
Processor Installation Drive. That is CPU. I would remove & then replace (re-seat).
Having mentioned that you replaced the Video Card I assume you know how to open the case & follow anti-static precautions.