In each module, the refreshing modes will adjust each array independently, since the controller must support a fine-grained optimization routine. On the other hand, DDR4 supports a low-power auto self-refresh, which does the standard thing of refreshing the contents of memory but uses an adaptive algorithm based on the temperature in order to avoid signal drift. In general, SR is used when idle for power saving, while AR is used when the system is busy. In general, SDRAM devices such as DDR3 RAM, use auto-refresh (AR) and self-refresh (SR) to perform refreshing of its content. Now that we’ve got that out of the way, let us discuss the differences between DDR3 and DDR4. It operates in a synchronous mode, synchronizing with the bus within the CPU. Now, depending upon the way it refreshes, DRAM is divided into multiple types, of which the most prominent one is SDRAM. Synchronous Dynamic Random-Access Memory (SDRAM) is much faster than previous, conventional forms of RAM and DRAM. The Dynamic RAM, as the name suggests, keeps on refreshing its content every few intervals. Technically, RAMs are of two types – Static and Dynamic. With the help of this new design, all the voltage drops are dependent on the IC only and can be corrected, thus improving the stability of the modules of the DDR4 RAM.īefore discussing the differences between the refresh algorithms of DDR3 vs DDR4, let us discuss a bit about RAMs in brief. This is done in order to ensure that a consistent voltage is applied across each of them individually rather than the whole module at once.
The new design that has been implemented in the DDR4 RAMs works by enhancing the lower voltage with the help of voltage reference ICs before each memory chip.
This, in turn, can cause a significant voltage drop, affecting stability. In DDR3 RAMs, a single voltage source is applied across the whole module. Also, as the demand for battery life in notebooks and ultrabooks increases, using a DDR4 RAM alongside the latest 14nm processors allow for increased usage without rushing towards a power socket. While it doesn’t sound like a lot, the quoted numbers end up saving 1-2W per module per system, which for a fully laden home-user desktop might approach 15W at the high end of savings over DDR3, but for a server farm with 1000 CPUs, this means a 15kW saving. The DDR4 RAM operates at a lower voltage of 1.2 volts as compared to DDR3’s 1.5 volts. Power consumption is another aspect which manufacturers like to minimize, and thanks to the new DDR4 RAM, it works out quite well for them. This has been made to make the routing process easier. Additionally, the PCB has been made thicker as well, raising the dimensions from 1.0mm on the DDR3 to 1.2mm now, which opens the scope for more signal layers. To accommodate the added pins, the modules have a raised height of 31.25mm, as compared to DDR3’s 30.35mm. This further decreases the overall per-pin contact as well. Furthermore, since the modules are of the same length, the pin-to-pin distance in the DDR4 RAM has been brought down to 0.85mm, as compared to DDR3’s 1.00mm. DDR4 has switched to a 288-pin package, which directly goes on to say that there will be an obvious boost in the bandwidth capacity, which we will discuss further in the article. The DDR3 RAM used a 240-pin package, that has been changed in the DDR4 RAM. To make the jump to newer technologies, the design is probably the first thing that has changed.