I am very confused with the numerous factors taken into account when choosing graphics cards, like the size, the 6 or 8 pin connectors, the BIOS, the power requirements, etc. All I know is I have a Dell XPS 8500 desktop, it has a Nvidia GeForce GT 620 graphics card installed, and I want a used one under $100 for a game that requires a minimum of Nvidia GeForce GTX 550 Ti level of graphics card (any brand but with similar/better qualities).
Are there any other recommendations for graphics cards that best suit my computer, or is the Nvidia GeForce GTX 550 Ti fine? How about the Nvidia GeForce GTX 660 Ti? Is a graphics card that is labeled "2048MB" performing way worse than the same type of graphics card labeled with "2GB"? What does that mean, why is there storage on graphics cards?
I'm not sure how to find out the power capacity of my specific desktop computer, and whether my BIOS or the 6-8 connector pins are compatible because I have never opened any computer before to see. Also, I've heard things about Legacy vs UEFI and how graphics cards can be incompatible with older computers because they run with UEFI, so how do these graphics cards do with my old desktop?