Everything you need to know about SD memory cards so you don't screw up your purchase

2024 Author: Malcolm Clapton | [email protected]. Last modified: 2023-12-17 03:44

If you think that when buying memory cards for your gadgets you only need to look at the supported format and size, you will have to be upset. There are at least five important points to keep in mind.

1. Compatibility

For most people, microSD is just a form factor, but it really isn't. You can easily insert any microSD card into a standard slot, but not all of them will work, since cards differ in many ways.

Format

There are three different SD formats in total, available in two form factors (SD and microSD):

• SD (microSD) - drives up to 2 GB, work with any equipment;
• SDHC (microSDHC) - drives from 2 to 32 GB, work on devices with support for SDHC and SDXC;
• SDXC (microSDXC) - drives from 32 GB to 2 TB (currently 512 GB maximum), only work on devices with SDXC support.

As you can see, they are not backward compatible. New format memory cards will not work on older hardware.

Volume

The manufacturer's declared support for microSDXC does not mean support for cards of this format with any size and depends on the specific device. For example, HTC One M9 works with microSDXC, but officially only supports cards up to and including 128GB.

One more important point is connected with the volume of storage devices. All microSDXC cards use the exFAT file system by default. Windows has been supporting it for over 10 years, in OS X it has appeared since version 10.6.5 (Snow Leopard), in Linux distributions exFAT support is implemented, but it does not work out of the box everywhere.

High speed UHS interface

SDHC and SDXC cards can support Ultra High Speed, which, when supported by hardware on the device, provides higher speeds (UHS-I up to 104 MB / s and UHS-II up to 312 MB / s). UHS is backward compatible with earlier interfaces and can work with devices that do not support it, but at standard speeds (up to 25 MB / s).

2. Speed

Classifying the write and read speed of microSD cards is as complex as their formats and compatibility. The specs allow four ways to describe card speed, and since manufacturers use all of them, there is a lot of confusion.

Speed class

The speed class is associated with the minimum write speed to the memory card in megabytes per second. There are four of them:

• Class 2 - from 2 MB / s;
• Class 4 - from 4 MB / s;
• Class 6 - from 6 MB / s;
• Class 10 - from 10 MB / s.

The cards operating on the high-speed UHS bus have only two speed classes so far:

• Class 1 (U1) - from 10 MB / s;
• Class 3 (U3) - from 30 MB / s.

Since the speed class designation uses the minimum record value, theoretically a second-class card may well be faster than a fourth-class card. Although, if this is the case, the manufacturer will most likely prefer to state this fact more explicitly.

Maximum speed

The speed class is quite enough for comparing cards when choosing, but some manufacturers, in addition to it, use the maximum speed in MB / s in the description, and more often not even the write speed (which is always lower), but the read speed.

These are usually synthetic test results under ideal conditions that are not achievable with normal use. In practice, the speed depends on many factors, so you should not focus on this characteristic.

Speed multiplier

Another classification option is a speed multiplier, similar to the one used to indicate the read and write speed of optical discs. There are more than ten of them, from 6x to 633x.

The 1x multiplier is 150 KB / s, that is, the speed of the simplest 6x cards is 900 KB / s. The fastest cards can have a multiplier of 633x, which is 95 MB / s.

3. Tasks

Choose the right card based on specific tasks. The biggest and fastest is not always the best. For certain usage scenarios, volume and speed may be overkill.

When buying a card for a smartphone, volume plays a greater role than speed. The advantages of a large storage device are obvious, but the advantages of a high transfer speed on a smartphone are almost not felt, since large files are rarely written and read there (unless you have a smartphone with 4K video support).

Cameras that shoot HD and 4K video are a whole different matter: speed and volume are equally important here. For 4K video, camera manufacturers recommend using UHS U3 cards, for HD - regular Class 10 or at least Class 6.

For photography, many professionals prefer to use several smaller cards in order to minimize the risk of losing all images in case of force majeure. As for the speed, it all depends on the photo format. If you shoot in RAW, it makes sense to invest in a microSDHC or microSDXC class UHS U1 and U3, in which case they will fully reveal themselves.

4. Counterfeits

No matter how trite it may sound, buying a fake under the guise of original cards is now easier than ever. Several years ago, SanDisk claimed that a third of SanDisk memory cards on the market were counterfeit. It is unlikely that the situation has changed much since that time.

Common sense is enough to avoid disappointment when buying. Refrain from buying from untrustworthy sellers and beware of offers of “original” cards that are much cheaper than the official ones.

Attackers have learned to counterfeit packaging so well that sometimes it can be very difficult to distinguish it from the original. It is possible to judge with complete confidence about the authenticity of a particular card only after verification using special utilities:

• - for Windows;
• - for Mac and Linux.

5. Quality

If you have already faced the loss of important data due to a broken memory card for one reason or another, then when it comes to choosing, you will most likely prefer a more expensive card of a well-known brand than an affordable "no-name".

In addition to the greater reliability and safety of your data, with a branded card you will receive a high speed of work and a guarantee (in some cases even a lifetime).

Now you know everything you need to know about SD cards. As you can see, there are many questions that you will have to answer before purchasing the card. Perhaps the best idea is to have different cards for different needs. This way you can take full advantage of the equipment and not expose your budget to unnecessary expenses.