What is RAM?
There are three key components that define the performance of a computer: the processor (CPU), storage drive (HDD or SSD), and memory (RAM). In order for any operation to run smoothly, all these elements should have the appropriate specifications. You may have the latest CPU and the fastest SSD, but with a slow or low-size RAM you would lose all the benefits those new technologies can offer you.
But what exactly is RAM? Why can it dramatically influence a device’s overall performance and what to look for if you want to buy a new computer, upgrade your current one, or even build one yourself? We’ll try to answer all these questions in this article, and hopefully, you’ll find some new insights about computer memory, and how to choose RAM for your specific needs.
Random Access Memory, known simply as RAM, is the component that holds all of the data your computer is using at any given time – the operating system and any applications that you start. Random Access means it can read and write data items in almost the same amount of time irrespective of the physical location of data inside the memory. This makes RAM about a hundred times faster than even the fastest SSD or hard drive, but it limits the amount of data this memory can hold, compared to the main storage device.
RAM is also a volatile type of memory, which can only store data as long as the computer is running. When the device is turned off, this component gets emptied. Think of it as your computer’s short-term memory, whereas the hard drive or the solid state drive are more like the long-term memory. But how do these two memory types work together? Why do we need both of them in a computer? Well, as mentioned previously, RAM works alongside the processor and storage drive, where all your programs and files are located. When you want to perform some task, let’s say edit a document – the processor transfers the program data of your file from the storage drive to RAM for short-term access and use. Because RAM is so much faster than an SSD, the results of any actions you perform in a given application should appear instantly (of course depending on the program, and RAM specs, but we’ll get to that a bit later).
DRAM vs SRAM
There are two widely used types of RAM: dynamic (DRAM) and static (SRAM). DRAM is the predominant form of memory used in modern computers, which requires constant power to hold on to stored data. We already explained its functionality above as people generally refer to it simply as RAM. SRAM on the other hand, doesn’t need constant power to hold on to data, is significantly faster than DRAM but it is a lot more expensive to produce. Because of that, it is mainly used in small amounts as cache memory inside the CPU.
From here on we’ll focus on DRAM, since it is the component in your computer that allows your system to perform most of its everyday tasks.
Since its invention in 1968, the dynamic random access memory went through many changes that would eventually improve its performance. It started as asynchronous, which means it had different clock speeds for the microchips in RAM to the processor. When the processors started to become more powerful, RAM couldn’t keep up with all the requests for data. This problem led to the introduction of SDRAM (synchronous dynamic random access memory). But again, this type of memory reached its limit quickly, since it transferred data in a single data rate.
Finally, around the year 2000, double data rate random access memory (DDR RAM) was developed. This moved data twice in a single clock cycle and allowed for the big developments we see in modern computers. DDR itself has evolved three times through DDR2, DDR3, and DDR4, which is the most recent technology, but the older DDR3 is still widely used.
What do all the numbers mean?
So far you would think that choosing memory for your computer means deciding between DDR3 and DDR4, and maybe go for DDR4 if the price seems reasonable, but actually there are more things to consider. When shopping for RAM or a computer that comes in multiple configurations, you usually see a variety of numbers related to its performance. We’ll try and explain them as simple as possible, so next time you see something like this – 8GB DDR3 1333MHz CL9 1.5V PC3-10600 – it will not confuse you.
Having more RAM in your computer reduces the number of times the processor has to read data from the HDD or SSD, an operation that takes much longer than reading data from RAM. But that doesn’t mean you should always look for the highest amount of RAM when comparing devices. It usually comes down to what type of applications you are using most often. As long as everything you’re doing on the computer takes up less RAM than your total, everything should run smoothly. Only if the RAM fills up will your computer then slow down significantly.
The safest storage size for most people is 8GB. This amount is more than enough for gaming, multiple open tabs in Chrome, streaming and playing a movie (even all at the same time). You could also easily work with 4GB if you’re looking for a lower-end PC or if you are performing some simple tasks like web browsing, text editing, video calling, etc. People that would benefit from 16GB or 32GB of RAM are video editors, professional photographers or others that have a specific use in mind, process huge files or work with multiple applications.
RAM speed is measured in mega-transfers per second. In the case of DDR RAM (double data rate), there are two transfers happening per clock. So, for example, if you see DDR-200 that means it can run at 100 Megahertz, and DDR3-1600 runs at 800 Megahertz. It’s a common mistake to refer to DDR3-1600 as 1600 Megahertz when it’s really 1600 mega-transfers. But note that it depends on the manufacturer, which number they choose to advertise. The official speeds of DDR3 RAM are 800, 1066, 1333, 1600, 1866, and 2133 Megahertz, so often you would see these instead of the mega-transfers.
When it comes to choosing RAM depending on the speed performance, once you get above DDR3’s 1600MHz, you can barely notice the improvements for simple tasks. So far, DDR4 RAM has introduced speeds going up to 4266MHz, but that doesn’t mean you’ll notice double the performance. These improvements usually show up when you’re using specific applications, process large files on a daily basis or perform any other demanding task.
The voltage affects how much heat your RAM produces and how much power it consumes. The most recent types of RAM are more efficient and consume less power, while the older standards consumed more. The standard voltage for DDR3 RAM is 1.5V, but some DDR3 sticks run at a more efficient 1.35V or a slightly more power-hungry 1.65V. DDR4 sets an even more efficient standard of 1.2V. The voltage can make a visible difference in portable devices, it can lead to longer battery life and higher-resolution screens. You should definitely go for low voltage RAM, but note that it’s slightly more expensive.
In a computer, latency is the time delay between asking for some data and having that data available to be used. In RAM specifications, this parameter is usually referred as CAS Latency, or CL or “access time”. Logically, the lower the latency is – the faster the RAM. So you if you see CL9 and CL11, the first option is definitely the one to choose.
RAM timings are usually a series of four numbers, for instance – 9-9-9-24 or 10-10-10-27, where the first number represents the CAS Latency explained above. The other three also refer to some time delay – the amount of clock cycles that it takes the memory to perform a certain operation. Without getting too technical, the smaller the numbers, the faster the memory.
Peak transfer rate
Another number you might encounter in RAM specifications looks something like this: “PC4-25600”. This represents the peak transfer rate, which is calculated by taking transfers per second and multiplying by eight (memory modules transfer data on a bus that is 64 data bits wide, and since a byte comprises 8 bits, this equates to 8 bytes of data per transfer). The number 4 after the “PC” refers to the DDR4 and if we divide the above number by 8 we see that it represents the DDR4 3200Mhz module.
As you can see, many of the numbers come down to the same thing and without much technical knowledge you can compare two different memory modules and conclude which one is more efficient and best for you.
There are a few more things to keep in mind, though. Spreading your RAM out over multiple sticks will not significantly improve your computer’s performance. Go for it if the price is similar, otherwise, one stick with the right capacity is perfectly fine. When it comes to mixing different brands of RAM, you shouldn’t encounter any problems, but note that if they have different speeds like 1333 and 1600, all RAM will automatically run at the slower speed. Also, do not mix completely different types of RAM like one stick of DDR3 and the other of DDR4, or laptop RAM with desktop RAM. If you remember these few guidelines, next time you shop for RAM the decision will be a lot more easy to make.