I currently have the AMD Radeon HD 7700 graphics card in my PC, but I need to add more video memory, so I need to use AMD CrossFire. Before I buy my graphics card, I was wondering if VisionTek Radeon HD 7750 was compatible with what I already have. I looked at the compatibility chart on the AMD website, and it said 7700 worked with 7750, but I'm not sure since it says "VisionTek". Thank you all!
Nope, vram does not stack, e.g. 2 + 2 is still only 2 recognised. Also many games are not crossfire supported, and possibly needing a new higher Watts PSU, you would do better buying a newer single 4GB/8GB card.
You would need to supply system specs INFORMATION REQUIRED WHEN POSTING A QUESTION for someone to offer suggestions of a possible suitable choice.