What is RAM?
Before we break down the various generations of RAM, i.e DDR4 vs DDR3 vs DDR2 vs DDR SDRAM, we should probably start with the basics. Firstly, DDR is RAM. If you have a computer, you are already using Computer RAM, whether or not you know or understand what exactly it does. RAM is basically computer data storage for programs currently in use. When you click on a program icon, the program loads onto RAM after which you can use it. Most RAM chips wipe their memory once the computer is powered off. That’s why you always need to load your programs.
What is DDR SDRAM?
The DDR in this write-up is all SDRAM. DDR SDRAM stands for Double Data Rate Synchronous Dynamic Random-Access Memory. Don’t let the big words shake you. The magic in SDRAM is that it synchronizes data transfer between the CPU and memory.
DDR SDRAM has seen a number of iterations since the year 2000 when the first DDR was released. With the advent of online shopping opening up new markets worldwide, consumers need a passing understanding of these computer specs before purchasing a device. DDR3 was the most popular SDRAM on the market before the release of DDR4. Since 2014, however, the current crop of computers come with DD4. This is only natural, given that each iteration of DDR comes with incremental performance improvements over the older generation.
Keep this in mind though; 4 GB of DDR2 is very different from 4 GB of DDR3. For one, it’s not interchangeable. You will need to either buy RAM appropriate for your computer or to replace the motherboard altogether. To clearly map out the differences in SDRAM, please have a look at this:
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DDR4 vs DDR3 vs DDR2 vs DDR
|SDRAM version||Release Date||Bus Clock|
DDR SDRAM has incrementally improved upon the performance and battery consumption over the years. The SDRAM chips initially started out with between 2.5~2.6 volts way back in 2000 for DDR. At the time, this was a breakthrough that took more than a decade of elbow grease. Currently, that figure is further down to as low as 1.05~1.2 volts in DDR4. While this might still not sound like much, it does its part helping computers to emit less heat, improve overall battery efficiency and power economy. For systems with a bunch of RAM chips, the effect is obvious when consumers get the power bill at the end of the month. More so, they spend less on cooling systems.
The addition of SDRAM into the equation saw an improvement in data transfer between CPU and memory. A CPU using SDRAM can process data even as it queues up other processes. More on that point, in a battle of DDR4 vs DDR3 vs DD2 vs DDR, the clear winner is DDR4, the newer, more powerful iteration which improves upon advancements by it’s predecessors.
DDR4 and DDR3 both have 8n prefetch architecture. These transfer 8 bits of data per cycle from the memory array to the memory internal I/O buffer in DDR4 and DDR3. In an 8n prefetch architecture, the internal I/O buffer will operate 8 times faster than the memory core. DDR2 comes with 4n prefetch to DDR’s 2n architecture. This number is 4 bits of data in DDR2 and 2 bits of data per clock cycle in the case of DDR SDRAM.
DDR5: The Holy Grail
JEDEC, the 300 member-strong semiconductor engineering standardization body gave us a strip-tease on what to expect in the next generation DDR5 SD RAM. As expected, JEDEC is vague about the details at this stage. But firstly, expect a further reduction in power consumption compared to DDR4. What’s more DDR5 will double the memory bandwidth and capacity of DDR4, for starters. DDR 5 is expected to support 1.1 operating Voltage and data transfer rates of between 3200 to 6400 Mbps with capacities ranging between 8 to 32GB.
It’s also rumored to be much cheaper than its predecessors. Unfortunately, we will have to wait till 2020 onwards for it to make it to regular computers. On Oct, 2020 SK Hynix announced the world’s first DDR5 Chip which supports transfer rate of 4,800 ~ 5,600 Megabit-per-second (Mbps), which is 1.8 times faster than the previous generation – DDR4. The company is focusing on premium server market first before moving to the consumer segment according to the companies press release.