What is the current OS installed on the system? When did the issue start? Please provide more info about the issue with the video card.
Are there any bluescreens / system crashes when you are playing games or watching HD videos?
Ensure you save all data first and then try flashing the BIOS - http://dell.to/29WcKn1- force the BIOS flash if required - http://dell.to/2hnhjs4
Try installing the video drivers from vendor site - http://bit.ly/1OwsREZ
Run a stress test on the system - http://dell.to/1NEc1Y4
Restart the system and press f12 key on startup - choose diagnostics. Let it run the diags and if you encounter any errors - make a note of the complete error and report the same to us. These are onboard diagnostics and they might possible pick some error if the hardware is not functional.
If there is no warranty, then you could contact our team to get a quote for a paid service call - http://dell.to/1vnT6CQ
Also, please click my DELL-username and write me a private conversation with the service tag and your contact details(Name and Email) for case records.
Let us know if you have any other queries.