With SD Cards, Spending More Really Does Speed Things Up

What do you get for your money? That's the question everyone looking to buy a piece of tech asks themselves. It also happens to be the question this recurring feature will try to answer. Is it worth spending extra on high-end gear, or do you get what you need with cheaper models? Every month, we'll look at some of the cheapest and most expensive products in a given category, testing each to see what their limits are and help you figure out when you can cheap it out, and when to plunk down some extra cash to get what you need.

High/Low: SD cards

So you've just bought yourself a nice new camera. You'll need an SD card to store all those images on. Do you save some scratch and go with the cheapest SD card, or do you splurge and opt for one of those expensive versions that come with names like Ultra or Extreme? At first glance, it seems like a no-brainer: The cheaper cards offer much more space for less money. So, why would anyone spend more on a smaller card?

The simple answer is speed. You'll pay more for an SD card that works faster. And a faster card might just help you make better use of your gadget.

SD cards are categorized into classes. Certain class designations guarantee certain speeds. A typical cheap card will be Class 4, meaning it can read and write data at 4 Megabytes per second (MB/s). Class 10 cards guarantee 10 MB/s, and the industry body that sets these standards recently added two faster standards: UHS-I (Ultra High Speed) and UHS-II that up the zippiness even more for pro users. As a general rule, the more expensive the card, the faster the data can be written and read to and from the card.

So how does this translate in the real world, and does it make sense to spend more for the higher speed?

We bought two microSD cards to find out: a $21 SanDisk mobile 32GB card, and a $46 SanDisk Extreme Pro 16GB card. The cheaper card is a "Class 4" that's designed for general use, while the more expensive one is a "Class 10" and UHS-I card designed for power users. One thing to note here: We used the microSD version of the cards with adapters to fit into the larger SD card slots, but SanDisk told us that these cards are functionally identical to their larger SD card-sized cousins.

First, we tested the cards in a MacBook Pro's internal SDHC reader, where we found that the Extreme card was much more, well, extreme. While the test programs could read data from the cheap card at about 23MB/s, the Extreme Pro card managed about 88.3MB/s. The difference was even more noticeable when writing data to the card: The cheap card could only handle a slow flow of data (under 5 MB/s), while the Extreme Pro card could handle a veritable flood: we clocked it at between 45 and 64 MB/s.

• Sandisk 32GB microSD

• Sandisk 16GB Extreme Pro micro SD

• Copy 2.4GB from SD Card to Mac drive

• 1 min 44 sec

• 30 sec

• Copy 2.4GB to SD Card in smartphone over USB

• 10 mins 21 sec

• 2 min 44 sec

So the Extreme Pro card is considerably faster. In the real world, this means you can get your photos off it much quicker. When we timed how long it took the same MacBook Pro to copy the results of a two-hour shooting session (2.46GB of photos) from the SD card to its internal drive, the cheap card took 1 minute and 44 seconds. The faster card took just 30 seconds. That's a pretty huge difference, and one that you'll find even more beneficial if you shoot RAW photos or long videos – both of which are notoriously large and slow to copy.

We also found the same large difference when copying files to a smartphone. Copying 2.4GB of assorted videos and music to the Extreme Pro card in a Samsung Note phablet took under 3 minutes. Copying the same data to the same phone with the cheap card took over 10 minutes. If you're the sort of person who likes to send a few TV shows and albums to your smartphone just before you leave on a trip, those extra 7 minutes could be the difference between a comfortable check-in and running to catch the plane.

The faster write speed of the Extreme Pro card also worked well when shooting photos. We tested this with a Panasonic DMC-GX1, which, when shooting JPEG images at the full 16-megapixel resolution, can capture about 4.3 frames per second. The Extreme Pro card made a significant difference here, but not the difference you might expect. It didn’t shoot photos any faster, because the GX1, like most modern cameras, stores images in its own internal memory, and then writes them out to the SD card.

Instead, the Extreme Pro card made a big difference in how many frames you could shoot at this speed…and what happened afterwards. We were able to shoot 22 frames at the full speed of 4.3fps, after which the camera slowed down to a speed of about 1.5 fps. Overall, we were able to shoot 40 frames in 20 seconds. With the cheaper card, it was only able to capture 15 frames before the camera slowed down. In 20 seconds, it only shot 21 frames. Again, the Extreme Pro card allows you to shoot quicker, for longer, and to shoot more consistently.

• Sandisk 32GB microSD

• Sandisk 16GB Extreme Pro micro SD

• Number of frames it can maintain 4.3fps speed for

• 15

• 22

• FPS afterwards

• 0.9

• 1.6

• Number of frames that can be captured in 20 seconds

• 21

• 41

So what's the trade off here? Well, the cheaper card is less than half the price ($21) and double the capacity of the Extreme Pro. That means you get double the space for music and video, and there are also plenty of situations where the speed of the card didn't make much difference. The digital camera we used could capture HD video with both cards, and even the slower card could handle writing that flow of data without issues. We also noticed no difference in everyday shooting between the two cards. For the snap, snap, snap of taking holiday photos, both cards were adequate. Playing back media from the cheap card on a cell phone also worked fine. We were able to watch high-quality video without glitches.

In the end, it comes down to how much speed matters to you. If you rely on getting the shot in your camera or need to rush photos from camera to laptop to Internet, spending more on a faster card makes a lot of sense. This is why the pros drop small fortunes on big, fast memory cards like the $120 Transcend 128GB UHS-I SDXC card. Faster cards also benefit anyone who takes photography seriously: A faster memory card helps you get more out of your camera. However, megabytes still matter. And for many users, the cheaper card undoubtedly gives you more of them.

• Sandisk 32GB microSD

• Sandisk 16GB Extreme Pro micro SD

• BlackMagicDesign Disk Speed Test, 5GB (Read/Write)

• 22.7 / 4.9

• 88.3 / 63.9

• Xbench Disk Test, Sequential Uncached 256K blocks (Read / Write)

• 23.9 / 6.7

• 153.7 / 45.9

- All speeds in MB/s, averaged over 3 test runs
- All timesaveraged over 3 test runs
- In-camera tests done with Panasonic DMC-GX1, card formatted in camera before test