Jedec fixes gddr5x memory standard

Standards organization Jedec has formalized the new gddr5x specification for video card RAM. The new standard is derived from gddr5 and the organization speaks of a doubling of the amount of available bandwidth.

In full the standard jesd232 graphics is called double data rate sgram. In the announcement, Jedec speaks of a throughput speed of 10 to 14 Gigabit per second as a target for the new standard. That would mean doubling compared to gddr5. This is achieved by doubling the prefetch from eight ‘data words’ per memory access to sixteen ‘data words’. Jedec promises that this will not come at the expense of the relative energy efficiency of the memory. In the long term, 16 Gigabit per second should be feasible.

The new memory standard is still very similar to the existing gddr5. For example, the same pseudo open drain signaling is used. That is why this new standard is not given the name gddr6. As a side effect, video card manufacturers do not have to make major changes to their cards before gddr5x can be used. The memory controller must be suitable for the new memory.

Although gddr5x is a step forward, it still falls short of the specifications of high-bandwidth memory, let alone hbm2, which is now also in production. However, Gddr5x is cheaper to produce and we may see this type of memory in low-end and midrange video cards and hbm is used in high-end video cards from AMD and Nvidia.

Slides from a Micron presentation on gddr5x, October 2015