First-time RAM buyers need to understand memory density and speed specifications. Density refers to the maximum amount of data a memory module can hold, while speed refers to the rate data can be transferred. When choosing between modules, prioritize getting higher density first, as it determines how much data can be stored. Higher speeds provide marginal benefits and only matter for intensive tasks like gaming, video editing and server use. Most users will not notice speed differences, so focus on getting the highest density that fits your budget.

1. First-time RAM buyers can get tripped up
by densities and speeds
Does “8GB 2666 MT/s RAM” make sense to you? If it looks like alphabet soup, you’re not the only one who
feels that way.
If you’ve never installed computer hardware and you’re considering a memory (RAM or DRAM) upgrade, you’re on
the right track to fixing a slow desktop or laptop. But your head might spin if you have to choose between 4GB 2400
MT/s, 4GB 2666 MT/s, 8GB 2400 MT/s, and 8GB 2666 MT/s. Even if you know they’re densities and speeds, which
option do you need? Here’s how to make that call.
How to read memory specs
An 8GB 2666 MT/s memory module, for example:
IS MORE MEMORY
OR FAST MEMORY BETTER?
Density, also known as capacity, is the maximum amount of data the
module can hold at once.
Speed, also known as frequency, is the amount of commands (megatransfers)
that the memory can send to the central processing unit (CPU) in a given period
of time, which then gets processed into what you see and do on your computer.
Density of 8 gigabytes (GB)
Speed of 2666 megatransfers
per second (MT/s).
Density or speed? Here’s the short answer
When you’re forced to decide, choose density. But (you knew there was going to be a “but”), it’s more of a priority
issue, not an either/or situation. Density is the first priority, speed the second.
DDR4 (the latest memory technology, which matters when figuring out compatibility) memory speeds generally range
between 2133 MT/s and about 3000 MT/s. DDR3 memory (common in older computers) speeds range from
1066 MT/s to 1866 MT/s. Let’s say, for example, you buy some RAM that’s rated at 3000 MT/s. If your computer’s CPU

2. MOVIN’ WITH
MEMORY
To understand the relationship between a
computer's memory density and memory speed,
imagine moving out of one house and into another
Memory density is like the size of the moving
truck – the larger the truck is, the more boxes
and furniture you can load into it
01
Memory speed is comparable to how quickly the
movers load and unload the boxes and furniture in
the moving truck
02
Increasing the size of the truck and the speed
of the movers makes moving faster and more
convenient, and the benefits of both are more
noticeable when there’s more to move
04
In this analogy, a bigger truck and faster movers are
both extremely helpful, but it's most important to have
everything you need packed up in the truck (memory
density) first so the movers (memory speed) can then do
their work more efficiently.
The roads, number of lanes, and speed limits
that the moving truck drives on are similar to the
limitations of your computer’s CPU, motherboard,
and other components
03
©2018 Micron Technology, Inc. All rights reserved. Information, products,
and/or specifications are subject to change without notice. Neither
Crucial nor Micron Technology, Inc. is responsible for omissions or errors
in typography or photography. Micron, the Micron logo, Crucial, and the
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Inc. All other trademarks are the property of their respective owners.
or motherboard can only run memory at speeds up to, say 2400
MT/s, the system will only run the memory at 2400 MT/s. There
are also maximum limits on densities, so you can’t install 64GB of
memory in a system that can only support 8GB.
How density and speed benefit what you do
Depending on how you use your computer, and what your
computer is capable of, you’ll experience the benefits of a memory
upgrade differently. Although it’s difficult to separate density from
speed and vice versa, here are a few activities and what you would
likely notice if you added density or speed.
Word processing
•• Going from 2GB to 4GB
-- Less waiting for letters and words to appear as
you type
-- Improved multitasking among multiple apps
-- Less chance of your computer freezing
•• Going from 4GB to 8GB or more
-- Near-instant responsiveness
-- Seamless multitasking
-- Almost no chance of your computer freezing
•• Going from 2400 MT/s to 3000 MT/s or more
-- Not many performance gains you’d notice
Verdict: You don’t need much RAM to make word
processing smoother. You only need enough to give
your computer extra room above the active data of
your operating system (OS).
Web browsing
•• Going from 2GB to 4GB
-- Improved responsiveness when opening
browser tabs and clicking links
-- Improved multitasking among multiple apps
-- Less chance of your computer freezing
•• Going from 4GB to 8GB or more
-- Near-instant responsiveness even with an
insane amount of tabs open
-- Seamless multitasking among multiple apps
-- Almost no chance of your computer freezing
•• Going from 2400 MT/s to 3000 MT/s or more
-- Not many performance gains you’d notice
Verdict: Web browsers are notorious RAM guzzlers
because they use so much active data, and as a
result, they’re often guilty of slowing your computer
down. More density or speed in your memory won’t
affect the speed of your Internet connection, but
your computer will run browsers more efficiently if
it has sufficient RAM.

3. What’s active data?
When you’re using your computer,
there are many operations,
processes, and commands going on
in the background that consume
RAM resources. These are what your
OS does behind-the-scenes – things
that make sure your computer, and
the apps on it, function properly. To
see what’s currently running on your
system, do this:
On Microsoft® Windows® systems,
press CTRL + Shift + Esc at the same
time
On Mac® systems, open the Finder
app, then click Applications >
Utilities > Activity Monitor
Streaming video
•• Going from 2GB to 4GB
-- Reduced risk of choppy or frozen playback caused by
too much RAM being consumed by the web browser or
other open apps
-- Improved responsiveness
-- Less chance of your computer freezing
•• Going from 4GB to 8GB or more
-- Very little chance of choppy or frozen playback caused
by inundated RAM
-- Near-instant responsiveness
-- Seamless multitasking
-- Almost no chance of your computer freezing
•• Going from 2400 MT/s to 3000 MT/s or more
-- Minimal; possibly more frames per second (FPS) during
playback
Verdict: Internet connection speed plays a more important
role than memory with video streaming. However, your
computer needs enough GBs of memory to run everything
else your system is doing so the playback isn’t choppy
or freezes.
Building spreadsheets
•• Going from 2GB to 4GB
-- Less waiting for letters and numbers to appear as you type
-- Less chance of your computer freezing
-- Improved seamless multitasking among multiple apps
•• Going from 4GB to 8GB or more
-- Near-instant responsiveness, even as spreadsheets become more complex
-- Seamless multitasking
-- Almost no chance of your computer freezing
•• Going from 2400 MT/s to 3000 MT/s or more
-- Minimal, but helps process the commands faster with massive spreadsheets
Verdict: Spreadsheets can grind your computer to a halt if they’re complex and don’t have
enough memory density to hold all the active data. If you’re constantly building large and detailed
spreadsheets, at least 8GB of memory is a must. Intensive tasks like this are also where the benefits
of memory speeds processing all that active data begin to kick in.
Photo editing, video editing, and rendering
•• Going from 2GB to 4GB
-- Less waiting for software to catch up to your clicks and commands
-- Improved multitasking among multiple apps, but still likely slow
-- Less chance of your computer freezing
•• Going from 4GB to 8GB or more
-- Near-instant responsiveness
-- Improved multitasking; closer to seamless with 16GB or more
-- Almost no chance of your computer freezing
•• Going from 2400 MT/s to 3000 MT/s or more
-- Possibly more FPS during playback

4. Verdict: Photo and video editing apps require more system resources than many other kinds of
software, and if you don’t have at least 8GB of RAM, your computer may not be able to run them
at all. Since they flood your system with active data, you need enough GBs of RAM to hold it all and
enough speed to process all the commands. Demanding apps like these will also benefit from a solid
state drive (SSD), which is much faster than a hard drive.
Gaming
•• Going from 2GB to 4GB
-- Improved responsiveness
-- Less chance of your computer freezing
-- Depending on the game, you may need more than 4GB just to play it
•• Going from 4GB to 8GB or more
-- Near-instant responsiveness
-- Improved ability to multitask between streaming, communicating, and other apps
-- Almost no chance of your computer freezing
•• Going from 2400 MT/s to 3000 MT/s or more
-- Possibly more FPS during gameplay, which makes the game more realistic
Verdict: Many games require at least 4GB of RAM to run, but it’s recommended to install at least 8GB
to run them well. And, because games use so much active data, memory speed can make an impact
while gaming – to a point. Some gamers overclock their system (that is, speed up the processor’s
clock cycle) but it takes technical knowledge, time researching how to do it, understanding the
benefits and consequences, and also risks voiding the computer’s warranty.
So when is paying more for that extra speed a good idea?
Faster speeds are a way to squeeze every ounce of performance out of
memory-intensive workloads, which translates into fewer delays that can
potentially cost time and money. These benefits are often imperceptible to a
person who casually uses their computer, but, as an extreme example, they’re
more noticeable in server deployments that are constantly bombarded with
massive memory demands. If you’re a designer, data analyst, videographer,
or gamer that uses memory-intensive apps and your margin of error is on
a scale of microseconds, then faster memory speeds paired with sufficient
density are often worth it.
The bottom line
When you’re shopping for RAM and you’ve found some that’s compatible with
your desktop or laptop, the range of speeds available probably isn’t significant
enough that the naked eye can truly notice a difference – depending on
how you use your computer. Unless you intend to use apps that flood your
computer with active data, you probably don’t need the fastest memory
modules on the market. Focus first on maxing out your system’s memory
density, then find the speed that best fits your needs and your budget.
©2018 Micron Technology, Inc. All rights reserved. Information, products, and/or specifications are subject to change without notice. Neither Crucial nor Micron
Technology, Inc. is responsible for omissions or errors in typography or photography. Micron, the Micron logo, Crucial, and the Crucial logo are trademarks
or registered trademarks of Micron Technology, Inc. Microsoft and Windows are either registered trademarks or trademarks of Microsoft Corporation in the
United States and/or other countries. Mac is a trademark of Apple, Inc., registered in the U.S. and other countries. All other trademarks are the property of their
respective owners. REVISION: 03/20/18