GDDR5

GDDR5 (Graphics Double Data Rate, version 5) is a type of graphics card memory the standards of which were set out in the GDDR5 specification by JEDEC. GDDR5 is the successor to GDDR4 and unlike its predecessors has two parallel DQ links which provide doubled I/O throughput when compared to GDDR4. GDDR5 SGRAM is a high speed dynamic random-access memory designed for applications requiring high bandwidth. GDDR5 SGRAM uses a 8n prefetch architecture and DDR interface to achieve high-speed operation and can be configured to operate in x32 mode or x16 (clamshell) mode which is detected during device initialization. The GDDR5 interface transfers two 32 bit wide data words per WCK clock cycle to/from the I/O pins. Corresponding to the 8n prefetch a single write or read access consists of a 256 bit wide, two CK clock cycle data transfer at the internal memory core and eight corresponding 32 bit wide one-half WCK clock cycle data transfers at the I/O pins.

Qimonda, a spin-off of Infineon, has demonstrated and sampled GDDR5 , and released a white paper about the technologies behind GDDR5 . On May 10, 2008, Qimonda announced volume production of 512 Mb GDDR5 modules rated at 3.6 Gb/s (900MHz), 4.0 Gb/s (1GHz), and 4.5 Gb/s (1.125GHz)..

Samsung had announced plans for the transition to GDDR5 by the beginning of 2008 . It had since announced that it had developed GDDR5 memory at 6.0 Gb/s at 512 Mb density.

Hynix Semiconductor has introduced the industry's first 1 Gib GDDR5 memory. It supports a bandwidth of 20 GB/s on a 32-bit bus, which enables memory configurations of 1 GiB at 160 GB/s with only 8 circuits on a 256-bit bus.

On June 25 2008, AMD became the first company to ship products using GDDR5 memory with its Radeon HD 4870 video card series, incorporating Qimonda's 512 Mb memory modules at 3.6 Gb/s bandwidth.