How can I detect the model of my graphics card?

I use Speccy. Its an awesome little free tool that give you all kinds of information about your system. It has a really nice UI, and you can download a portable version so you can run it without installing.

Its made by the same people as CCleaner, website here.

Two or three years later, when it comes time to upgrade your computer, that tag or sticker may be long gone. Speccy was designed as a free electronic "what's inside" sticker for your PC.

Hope that helps.

TechPowerup's freeware GPU-Z works for me.

SIW or System Information for Windows provides more info on system, hardware and drivers than I know what to do with so may be what you need.