DDR3 - Evolution continues
When we are talk about changes in chipsets, processors and many other computer components, man always think of RAM. Not only because the evolution there takes place with much lower pace, but the fact that most consumers pay more attention to the amount of memory rather its type. We do not comment the speed - the things here are evern more complex. Whether DDR333, DDR400, DDR600, DDR2-800 or even 1066 MHz - only enthusiasts and fans of overclocking are interested in these exact values. And while we rely on the reduction of timing in DDR2, currently on the market is steady entering a new generation - DDR3. Familiar to many manufacturers of graphics cards, DDR3, as regards the use of system memory is a little different level.
The transition from SDR to DDR was noted as the first major change in the transmission of data - it can now be processed faster. Thus 200 MHz effectively turn into 400, so that DDR400 memory is actually operating at 200 MHz, and DDR333 - 166.
The move to DDR2 was accompanied by a doubling of the real rate of I/O buffers and preserving the frequency of cells. Thus DDR2-533 memory cells work on 133 MHz, while the I/O buffers are already operating at 266 MHz, from where we receive the effective 533 MHz. If you compare the frequencies of DDR1 and DDR2, it appears that at 800 MHz DDR1 effective cell will operate at 400 MHz, while DDR2 will be 200 MHz.
Increasing latency with DDR2 works exactly in the opposite direction of the effective bandwidth, which is why at standard settings and the same frequency DDR1 quite some time had an advantage. This DDR2 which failed to overcome its shortcomings, was much higher frequency, lower latency and, of course, reduced consumption (caused by the lower frequency of memory cells).