Graphic card memory and system memory have nothing to do with each other. You can use a GDDR5 graphics card on a motherboard that accepts only DDR3 system memory. Yes you should. If you are running a high end card you would be lucky for that system NOT to start.
Likewise, what does gddr5 mean on a graphics card?
GDDR5, an abbreviation for double data rate type five synchronous graphics random-access memory, is a modern type of synchronous graphics random-access memory (SGRAM) with a high bandwidth ("double data rate") interface designed for use in graphics cards, game consoles, and high-performance computation.
Is a ddr5 graphics card compatible with a ddr4 motherboard?
Yes! Graphics cards are cross compatible with the DDR2-DDR4 Motherboards. Long Answer: As long as your motherboard has a pci express slot you can fit any graphics card even if your motherboard supports DDR3 or DDR2 ram.