An Introduction to RAM
There are many types of computer memory; here we focus on RAM, or random access memory, the temporary memory accessed by the CPU to perform various tasks.
RAM is a integral component of your computer, responsible for processing data. It is called RAM because the CPU can “randomly access” memory cells on the RAM chip. It is much faster to locate data in RAM than to access other types of memory, such as the hard drive. Because of this, RAM is often contrasted with serial access memory, or SAM, which must be accessed sequentially until your computer locates the relevant data.
How RAM Works with Your System
RAM is managed by a memory controller embedded in the CPU, the central processing unit found within a computer that is responsible for data retrieval. If the CPU always had to access the hard drive each time, the recall of data would be slowed significantly. By storing the information in other types of memory, such as RAM, the CPU is able to access it much quicker, and therefore the operating system is maintained through the RAM, as are any applications. When you save or close a file, this is then relocated to the main storage space and removed from the RAM. Because of this, RAM is considered a ‘volatile’ type of memory, meaning that when the computer in turned off, the contents of the memory is lost. This result is a smoother, faster, less power-intensive system.
Types of RAM: Static RAM (SRAM) and Dynamic RAM (DRAM)
RAM is generally divided into two categories: static RAM (SRAM) and dynamic RAM (DRAM). Both are a volatile form of memory, but the main difference is the technology used to hold data. Whilst DRAM refreshes thousands of times per second, SRAM, by contrast, does not need to refresh and so is typically faster. However, DRAM is the standard when it comes to consumer level RAM because SRAM is more expensive and generally used for memory caching. Below is a table of the different types of SRAM and DRAM:
SDRAM and DDR
SDRAM (Synchronous Dynamic Random Access Memory) was developed in the 1990s to meet the needs of more powerful computers. Traditional DRAM used an asynchronous interface which worked independent of the processor, which was not ideal since DRAM was unable to keep up with the processor speed. SDRAM synchronises the memory's responses to control inputs, enabling it to queue processes for the quick execution of tasks.
DDR and its subsequent models is the most commonly used type of RAM, and is current standard for consumers. Since its introduction, it has gone through several development stages. DDR (Double Data Rate) was the initial model, introduced in 2000. DDR RAM is able to send and receive signals twice per cycle, as opposed to one, meaning that data transfers were twice as fast. It also decreased the clock rate, consumed less energy, and achieved faster speeds. DDR2 is double the rate of DDR. This was then succeeded by DDR3, which features four clock speeds: 1333Mhz, 1600Mhz, 1866Mhz, and 2133Mhz. Finally, DDR4 is the latest model, and provides a greater range of clock speeds and timings, lower power consumption, as well as reduced latency.
Considerations when installing RAM
Is More RAM Always Better?
Increasing the amount of RAM won’t necessarily lead to faster processing speeds. First, your hardware must physically match the RAM you want install. Since DDR DRAM is the standard, it’s important to ensure that your hardware is compatible; DDR, DDR2, DDR3 and DDR4 chips all feature a unique number of pins. If the RAM you purchased does not match the version required for your motherboard, it will not be physically possible to install it.
A second consideration is the clock speed. For the most part, the motherboard will determine the type of RAM that can be installed in the computer. The memory specs of your machine will have this information. If the motherboard supports DDR3 memories up to 1,333 MHz, then it’s advisable to use RAM of the same power. There are two reasons for this: anything less and your computer won’t achieve its full performance potential, and anything more could mean that the processor is unable to run at the same pace, causing the computer to lag.
A second thing to note is that today’s CPUs have built-in memory controllers showing what RAM is supported. Typically these match those found on the motherboard. However, in some cases the motherboard will allow you to install RAM at a clock speed that exceeds the official maximum supported by the memory controller.
CL: Column Access Strobe (CAS) Latency
CL or CAS latency is the time taken for the memory controller to signal the memory module to access a particular memory column on the RAM. It is the time delay between when a command is entered and executed. There are two variables: the number of clock cycles, and the duration of each one. CAS latency is expressed as number; on DDR RAM this will appear as a code such as CL14. As a rule, the lower the CAS latency, the faster it is.
A fourth consideration is voltage. Most DDR3 RAM runs at 1.5V, but it can range from as low as 1.25V to as high as 1.8V. DDR4 RAM features a new voltage called VPP; the standard for DDR4 is 1.2V, but it goes as low as 1.05V. There are slight differences to note: when compared with DDR3 RAM, DDR4 provides higher transfer rates at a lower voltage, which is better for performance and system stability over time. Whilst increasing voltage does improve performance, increasing the voltage of RAM can create problems because a higher voltage leads to more heat generation and power consumption. For overclocking, it should not be necessary to exceed 1.7V.
Dual, Triple or Quad-Channel
Increasing the number of channels increases the speed between the RAM and the memory controller. Dual-channel architecture doubles the available memory bandwidth from 64 to 128 bits, triple-channel to 192 bits, and quad-channel to 256 bits. Because modules will be accessed at the same time, it’s important to use identical RAM: same capacity, timings, and clock rate. It’s also advisable to use the same brand for increased synchronicity.