GDDR4 will start appearing at the end of this year

By the end of this year there will already be a new memory technology to replace GGDR3. The GDDR4 memory is build upon the GDDR3 standard. It's not really a revolution, just a few special tweaks to allow higher clock speeds on graphics cards using the new GGDR4 memory. GDDR4 is developed by JEDEC and several graphics companies like ATI and NVIDIA.

The GDDR3 evolves from GDDR2, but will sport some pretty important differences. Firstly, GDDR3 makes use of a single-ended, unidirectional strobe that separates the reads and writes. GDDR2, by contrast, uses differential bi-directional strobes. Secondly, GDDR3 utilizes a “pseudo-open drain” interface technique that is based on voltage rather than current. This was done so that graphics chips can be compatible with DDR, GDDR2 and GDDR3. Like GDDR2, GDDR3 interface uses 1.8-Volt SSTL. Such memory is generally better suited for point-to-point links used on graphics cards and allows the GPU developers to reach the new performance and feature heights with their products.

The current goals for the GDDR4 are to complete the process of standardization by the end of 2004 and push up the frequencies towards the 1.40GHz (2.80GHz effective) level. Lower clock-speeds, e.g. 1.00GHz (2.00GHz effective) are achievable by the GDDR3 technology, according to Samsung Electronics, who plans to debut such memory by the end of the year.

Source: X-bit Labs