When you talk about form factor, are you referring to the MB size, or the box type. I want to buy an upgrade for my H50-55 but I keep seeing this form factor stuff. how do I find out what mine is? Also does the graphics card have to be ddr3 when the ram is? Thanks
"form factor", regarding motherboards, is various sizes of the ATX standard.
What are you looking to upgrade? If you're changing the motherboard, the case you currently have is a trivial consideration.
A motherboard change generally requires new CPU and new RAM. From a prebuilt system, you often have to change the PSU as well.
Given all that stuff...a new case is just part of the parts list.