MT/s vs. MHz (Datarate vs. Frequency) in RAM Explained

Random Access Memory (RAM) is an essential component in every computer. RAM is a short-term memory bank for all the data your processor is currently working on. Since a computer processor is a fast-switching device that processes data in the gigahertz, it needs fast memory to keep feeding it all the data it needs to execute tasks at blazing speeds.

RAM speed is currently measured and advertised in megahertz (MHz). This, however, is being challenged by numerous people claiming that it should be mega transfers per second MT/s.

So, what’s the better measurement for RAM?

What Is Megahertz (MHz)?

Megahertz (MHz) is a measurement of frequency. Mega means a million, while hertz is a unit of frequency equal to one cycle per second. So, if you put it together, it means a million cycles per second.

So, what frequency does it measure exactly?

Megahertz can be used in just about anything where an instance is repeated. For RAM, however, MHz is used to measure the frequency of digital signals in the form of square waves.

Here is what a square wave looks like:

Square Wave Illustration

The peaks signify that voltage is present, while lines at the base signify no voltage. Computers use these up-and-down voltages to make square waves which are then converted to binary (1s, 0s).

What Are Megatransfers Per Second (MT/s)?

Megatransfer is a unit measurement for data rate in megabytes. One megatransfer is equivalent to one megabyte. If you time megatransfers in seconds, you get a logical way of measuring the speed of RAM in terms of how much data you can transfer per second.

Explaining Data Rate and Frequency

RAM speed is one of the two key factors when deciding what RAM to buy. RAM speed is either measured in MHz or MT/s. To understand why RAM manufacturers use MHz and why some people heavily disagree with this measurement, let’s talk about data rate and frequency, how it measures RAM speed, and how effectively it communicates the overall performance of RAM.

RAM modules, just like any other modern digital storage device, are made of transistors that act like switches. These switches function like the regular switches you use to turn the room lights on and off. In electronics, an on switch denotes 1, and an off switch means 0. These 1s and 0s (also known as binary numbers) compose all the data running on your system.

When we measure RAM speed using frequency, we measure how fast these transistors can cumulatively switch per second. So, if your RAM indicates a RAM speed of 3,600 MHz, you can logically expect its transistors to switch a total of 3,600,000,000 times per second.

As for measuring RAM speed using data rate metrics like MT/s, RAM’s frequency or clock speed doesn’t necessarily dictate how much data it can transfer per second. When measuring RAM speed using data rate, we measure the total bandwidth the RAM can transfer in an out of its memory modules. So, if your RAM indicates a RAM speed of 3,600 MT/s, you can expect it to transfer a maximum of 28.8 Gigabytes of data per second.

Why Using Megatransfers is Technically Correct

As discussed earlier, MHz is a measurement of frequency, while MT/s is a measurement of data rate. If you look at the current top RAM manufacturers, such as Samsung, Micron, and SK Hynix, you’ll see their RAM products are all measured in MHz (frequency). Although most PC builders are okay with this way of advertising RAM speed, it doesn’t mean it’s correct.

Single Data Rate

When Synchronous Dynamic Random Access Memory (SDRAM) was first introduced in the early 90s, using frequency metrics like MHz was the correct way of indicating RAM speed. This was because data was being transferred in sync with the clock speed of the RAM. So, if the RAM runs on a frequency of 400 MHz, its data rate should be the same as its clock speed, which is 400 MT/s.

Dual Data Rate

But with the introduction of Dual Data Rate (DDR) in RAM, data rate (MT/s) and frequency (MHz) are no longer on a 1:1 sync. Instead, DDR is a technology that doubles the data rate in regular SDRAM. By moving data on both the rising and falling signals of a square wave, a DDR RAM can transfer twice the data while running at the same clock speed.

This, however, doesn’t mean that measuring RAM speed using MHz is wrong, nor is using MT/s. Both data rate and frequency are good measurements to indicate RAM speed. The problem is with the numbers that RAM manufacturers use to advertise their products.

It has become the standard for RAM manufacturers to advertise their products to run at double the clock speed. For example, if you check your computer’s RAM speed, you’ll likely see standard RAM speeds such as 2,400-4,000 MHz—which is incorrect. These numbers actually came from how much data DDR RAM can transfer per second (MT/s) instead of its clock speed (MHz). So, instead of 3,600 MHz, it should be 3,600 MT/s or 1,800 MHz.

Why Does Everyone Still Use MHz?

Although using MT/s is the proper way of measuring RAM speed, RAM manufacturers and many people still prefer to use MHz.

Before the introduction of DDR, RAM modules were transferring data at Single Data Rate (SDR). This meant that RAM used to transfer data per clock cycle. So, if the RAM speed was 800 MHz, the data rate was also 800 MT/s. But with the introduction of DDR, RAM can now transfer twice the amount of data per clock cycle.

This caused RAM manufacturers problems in terms of advertising specifications. Unlike today, where information can easily circulate through the internet, back then, many people wouldn’t have been impressed if you were to advertise DDR RAM with almost the same numbers as the previous year. They might have even opted to buy SDR RAM.

Using MT/s instead of the usual MHz might have also caused further confusion. So, to communicate how fast and impressive the new DDR RAM products were, manufacturers had to show the bigger numbers (MT/s) while still using the usual MHz to make it easy for people to understand. This, of course, continued until today, when MHz is still used instead of MT/s.

Both MHz and MT/s are Good Metrics for Measuring RAM Speed

Both frequency (MHz) and data rate (MT/s) are good metrics for measuring RAM speed. MHz measures RAM speed by how many times it can switch voltage per second, while MT/s measures RAM speed by how much data it can transfer per second.

Although RAM speed is currently advertised in MHz, even though the numbers mean MT/s, as long as it communicates to you how fast your RAM is running, this shouldn’t be a problem. The best thing to do is to ignore the labeling metric and just stick with the numbers.

Source link

Leave a Reply

Your email address will not be published. Required fields are marked *