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Graphics DDR SDRAM (GDDR SDRAM) is a type ofsynchronous dynamic random-access memory (SDRAM) specifically designed for applications requiring high bandwidth,[1] e.g.graphics processing units (GPUs). GDDR SDRAM is distinct from the more widely known types ofDDR SDRAM, such asDDR4 andDDR5, although they share some of the same features—includingdouble data rate (DDR) data transfers. As of 2025[update], GDDR SDRAM has been succeeded byGDDR2,GDDR3,GDDR4,GDDR5,GDDR5X,GDDR6,GDDR6X,GDDR6W andGDDR7.
GDDR was initially known asDDRSGRAM (double data rate synchronous graphics RAM). It was commercially introduced as a 16 Mb memory chip bySamsung Electronics in 1998.[2] Compared to DDR SDRAM which is byte-accessible, GDDR SDRAM is block-accessible.[3]
| Module type | Chip type | Memory clock | Transfers/s | Transfers/clock | Transfer rate | |
|---|---|---|---|---|---|---|
| 32 lanes | GDDR2 | 400–500 MHz | 0.8–1.0 GT/s | 2 | 25.6–32.0 Gbit/s | 3.2–4.0 GB/s |
| 32 lanes | GDDR3 | 400–1000 MHz | 0.8–2.0 GT/s | 2 | 25.6–64.0 Gbit/s | 3.2–8.0 GB/s |
| 32 lanes | GDDR4 | 868–1126 MHz | 1.7–2.3 GT/s | 2 | 55.6–72.1 Gbit/s | 6.9–9.0 GB/s |
| 32 lanes | GDDR5[4] | 1000–2000 MHz | 4.0–8.0 GT/s | 4 | 128.0–256.0 Gbit/s | 16.0–32.0 GB/s |
| 32 lanes | GDDR5X[5] | 1000–1808 MHz | 8.0–14.5 GT/s | 8 | 256.0–462.8 Gbit/s | 32.0–57.9 GB/s |
| 32 lanes | GDDR6 | 1375–2500 MHz | 11.0–20.0 GT/s | 8 | 352.0–640.0 Gbit/s | 44.0–80.0 GB/s |
| 32 lanes | GDDR6X | 1188–1438 MHz | 19.0–23.0 GT/s | 16 | 608.0–736.0 Gbit/s | 76.0–92.0 GB/s |
| 64 lanes | GDDR6W | 1375 MHz | 22.0 GT/s | 16 | 1408.0 Gbit/s | 176.0 GB/s |
| 32 lanes | GDDR7 | 1750–2500 MHz | 28.0–40.0 GT/s | 16 | 896.0–1280.0 Gbit/s | 112.0–160.0 GB/s |
(1 lane is equivalent to 1 bit/transfer.)
