GDDR3 evolves from DDR-II, but still has some pretty important differences. Firstly, GDDR3 makes use of a single-ended, unidirectional strobe that separates the reads and writes. DDR-II, by contrast, uses differential bi-directional strobes. Secondly, GDDR3 utilises 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, DDR-II and GDDR3. Like DDR-II, GDDR3 interface uses 1.8-Volt SSTL. Such memory is better suited to point-to-point links used on graphics cards and allows GPU developers to reach the new performance and feature heights with their products.