Perhaps someone has already answered this but I couldn't be bothered to read through everyone's response. The main difference between DDR5 and GDDR5 will be the voltage. This stems from when GDDR2 and 3 were introduced for RAM designed specifically for the needs of graphics cards. I guess that means performance on a graphics card using GDDR5 would be better than that using DDR5... but I'm in no position to know for definate. By the way, you can have DDR memory on graphics cards, that's how it always used to be.