DDR1 vs DDR2 - Perfomance Comparision

	DDR	DDR2
Data Bus	64 bits	64bits
Data Rate	200/266/333/400 Mbps	400/533/667 Mbps
Bus Frequency	100/133/166/200 MHz	200/266/333 MHz
DRAM Frequency	100/133/166/200 MHz	100/133/166 MHz
Package Type	TSOP-II	FBGA
Densities	256MB 512MB 1GB	256MB 512MB 1GB
Voltage	2.5V	1.8V
Prefetch Size	2 bits	4 bits
Burst Length	2/4/8	4/8
CAS Latency	1.5, 2, 2.5	3+, 4, 5
Write Latency	1T	Read Latency -1

There are a number of upgrades that come with the new DDR2 technology over DDR1 memory. DDR2 memory is of course faster, and will ultimately reach clock speeds of 667MHz or higher as opposed to the top functional speed of DDR1 at 400MHz. The higher speeds of DDR 2 memory allow it to have up to 10.6GB per seconds of throughput - quite a bit more than DDR1 memory which maxed at 6.4GB per second. The feature that makes these higher speeds practical is the reduced power consumption of DDR2, which runs at only 1.8 volts. Heat is one of the real banes of IC's, and the faster you try and clock a chip the hotter it runs and the less reliable it gets. One of the speed limitations of DDR1 was that at 2.5 volts created too much heat and was simply too hot to run consistently at speeds greater than 400MHz. DDR2's 1.8 volts combined with a much smaller (FBGA) chip package goes a long way towards solving the heat issue at higher speeds.