The list of differences between GDDR-3 and GDDR-1 memory is remarkably short. Basically, where GDDR-1 modules required 2.5V, the newer GDDR-3 chips use 1.8V (Micron) or 1.9V (Samsung). Also, the GDDR-3 specification calls for an on-die termination. Both of these improvements allow the chips to be run at much higher frequencies. Samsung demonstrated the modules with the highest frequency to date, running at no less than 800MHz (1600MHz DDR). In the future, expect to see chips with even higher clock speeds. The newer technology has one disadvantage compared to GDDR-1, namely much higher CAS latencies (CAS read latency). In practice, this means that GDDR-1 modules will be slightly faster than GDDR-3 chips at the same clock speed.
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