How RAM Timing And Speed Affect The Performance Of Your Computer

In the world of computing, more is almost always better. Most users are aware that a processor with a higher megahertz or gigahertz speed is preferable. The benefits of having more RAM (also known as gigabytes of memory) are also fairly obvious. However, you might be perplexed by another stat related to your RAM: speed.

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What does your RAM’s speed rating actually mean, then? The solution is straightforward, but the actual implications for the performance of your system are subtle. Simply put, it’s probably not as significant as the RAM maker would have you believe.

What RAM Speed Ratings Indicate

The data transfer rate of your RAM module is expressed by its speed rating. The greater the number, the more quickly your computer can store and retrieve data from local memory. The formula for calculating the exact speed rating varies slightly depending on the version of DDR memory in your computer. It is no longer just a clock speed expression, as it is with a processor, but rather a combination of hardware factors. However, in general, faster is better.

As we get into the terminology, things start to become difficult. Although the speed rating is typically stated in simple “DDR” terms, the outdated PC2/PC3/PC4 standard is still in use. These numbers generally correspond to the speed rating corresponding to the generational standard: “DDR3 1600 RAM” is also labeled as “PC3 12800,” “DDR4 2400 RAM” is also labeled as “PC4 19200,” and so on.

This is a technicality based on the old bit and byte data expression—eight bits equal one byte. So, if the first number is DDR 1600 in million bytes per second capability, the second number is PC3 12800 in million bits per second capability. 12800 divided by eight equals 1600, so these are two different ways of saying the same thing. In general, sticking to the first “DDR2/3/4/5” speed rating will make things easier.

What RAM Timings Indicates

Each RAM module has a rating for something called timings in addition to a standard speed rating. Four numbers are used to represent this, such as 5-5-5-15 or 8-8-8-24. This discussion of the precise time it takes the module to access individual bits of data across columns and rows of the memory array involves some advanced computer science topics. This group of numbers, however, is typically referred to as “latency” for the sake of simplicity.

The faster the RAM module can access its own hardware, or latency, the better in this particular situation. Lower latency results in quicker data access, quicker data transfer to the CPU, and quicker overall computer operation. Lower latency is a benefit of more expensive, higher-quality RAM, and enthusiasts can increase both this rating and the RAM’s clock speed.

Despite this, the differences in latency are so negligible that you’re unlikely to notice any real differences between RAM with a higher or lower latency unless you’re running industry-level server operations or numerous virtual machines.

How Does This Affect Your PC?

It’s true that faster, lower latency RAM will improve your computer’s technical performance, but because it operates at such a fundamental level, it’s difficult for us mortals to actually notice the difference. If Data from Star Trek and C3P0 from Star Wars can calculate the probability of survival in one billionth of a second and two billionths of a second, respectively, does it really matter which one you ask?

Your computer will perform better in some benchmark tests if you have faster RAM, but for the majority of users, having more RAM available is almost always preferable. So, whenever you’re deciding between buying 16GB of DDR4 RAM with a speed rating of 2400 or 8GB of DDR4 RAM with a speed rating of 3200, always choose the latter. It also means that it is rarely worthwhile to overclock RAM in the system BIOS.

This is especially true in the case of gaming. Games will primarily use the video card’s own memory (labeled as “GDDR,” specifically created for visual applications) if your computer has a discrete graphics card to handle these tasks.

It should be noted that since your graphics card’s memory is mounted directly onto the graphics card PCB, the end user cannot upgrade it. Once more, picking a card with more memory over one with faster memory is generally a better choice.

When using computers with integrated GPUs, such as those made by AMD’s Accelerated Processing Unit series or non-discrete Intel designs, faster RAM can improve visual performance. The reason for this is that the setup’s reliance on system memory for graphics performance. For machines that are frequently accessed from various points, such as a busy web server or a virtual machine host, it can also make a more noticeable difference. It simply isn’t a big deal for most users.

DDR2, DDR3, DDR4, DDR5, and Speed Compatibility

Different generations of RAM are available, with updated standards enabling ever-faster access to the data kept in memory. We’re currently using DDR version 5, which replaced the original DDR standard, also known as “Double Data Rate,” which replaced Single Data Rate RAM back in 2000. As of early 2023, DDR5 RAM is still fairly new, and the majority of consumer PCs still frequently use DDR4 RAM.

Performance was improved with each new DDR version because the memory bus and speed capabilities of the RAM module format were expanded. However, it’s crucial to keep in mind that the standards are frequently neither backwards nor forwards compatible. You can only use DDR3 memory, not DDR2 or DDR4, if your laptop or motherboard is rated for DDR3 memory modules. Since the physical slots for the various standards don’t even correspond, installing the incorrect DDR standard should be impossible.

One notable exception is that, with the appropriate motherboard, Intel’s 12th-generation processors can support either DDR4 or DDR5 memory. The notch on DDR5 is in a different location than on DDR4, preventing DDR4 from being inserted into a motherboard that needs DDR5, or vice versa. DDR5 has the same number of pins as DDR4, but it has a different number of pins.

With regard to speed ratings, though, that is not the case. RAM slots on a motherboard can function without problems at speeds lower than their maximum. Therefore, if your motherboard supports DDR4 RAM at speeds of up to 3600MHz but you found some great modules with speeds as high as 2400MHz, feel free to install them.

Be aware that your motherboard might not initially support the advertised speed of your RAM. If you purchase DDR4-3600 RAM and your motherboard only supports DDR4-3400, it may still be clocked at the lowest setting—say, DDR4-3000—by default. You should enter the BIOS of your computer and adjust the speed there, either by turning on Intel’s extreme memory profile (XMP) or manually adjusting it.

Last but not least, keep in mind that installing RAM DIMMs that are not compatible (and thus have different speed and timing ratings) is typically acceptable because your motherboard is capable of recognizing and managing the various hardware. Nevertheless, in every situation, the system will slow down to match the slowest memory module it can access, so buying faster RAM to mix with slower RAM doesn’t really offer any advantages. It’s best to mix new and old RAM whenever you can.