GDDR是Graphics Double Data Rate的缩写，为显存的一种，GDDR是为了设计高端显卡而特别设计的高性能DDR存储器规格，其有专属的工作频率、时脉、电压，因此与市面上标准的DDR内存有所差异，与普通DDR内存不同且不能共用。一般它比主内存中使用的普通DDR存储器时钟频率更高，发热量更小，所以更适合搭配高端显示芯片。
英语百科
GDDR SDRAM
Graphics DDR SDRAM (GDDR SDRAM) is a type of synchronous dynamic random-access memory (SDRAM) specifically designed for graphics processing units (GPUs). GDDR SDRAM is distinct from the more widely known types of DDR SDRAM, such as DDR3, although they share some of the same features—including double data rate data transfers. As of 2014, GDDR SDRAM has been succeeded by GDDR2, GDDR3, GDDR4, and GDDR5 SDRAM.