While upgrading your Steam Deck’s SSD is easier than you might think, it’s still a fairly complex procedure. Expanding your Steam Deck’s storage with an SD card is way simpler and doesn’t require opening the thing. But does using slower SD cards increase game loading times? Let’s find out.
Not All SD Cards Are Equal on the Deck
The Steam Deck has an SD card slot that supports UHS-I —also known as UHS-1— SD cards, topping out at about 104MBps for read and write performance. In other words, if you plan on getting an SD card for your Deck, you’re limited to UHS-I models. But not all UHS-I SD cards are equal.
On the one hand, you’ve got older models with read and write speeds of 50MBps or less, notably below the Deck’s SD card slot specs. On the other hand, some high-end UHS-I cards feature read and write speeds that go over the Deck’s max specs. For instance, Samsung’s latest high-end SD card lineup, the Pro Plus, features read rates of up to 180MBps and up to 130MBps write performance.
UHS-I SD cards come in two flavors regarding minimum read/write speed: UHS Speed Class 1 (U1) models have a minimum read/write performance of 10MBps, while UHS Speed Class 3 (U3) cards have a minimum read/write speed of 30MBps.
You also have the A1 and A2 cards —also known as Application Performance Class 1 and 2— featuring higher random read and write speeds than non-A1/A2 models, which should lead to faster game loading times since loading a game is more or less a random read operation.
So, if you’re in the market for an SD card for your Steam Deck, should you aim for a U3/A2 SD card or settle for a more affordable U1/A1 model? Or maybe you can get away with getting a budget U1 card that doesn’t even feature the A1/A2 rating? Let’s find out by comparing three UHS-I SD cards: a budget U1 model, a U1/A1 SD card, and a U3/A2 unit.
These Are the SD Cards We’re Testing
Below you can see the three SD cards we’re benchmarking. The first is the budget Silicon Power Elite model with the U1 label but without the A1 or A2 rating. Next to it is the SanDisk Ultra SD card that features U1 and A1 ratings. Finally, the fastest SD card on this test, at least specs-wise, is the Samsung EVO Plus U3/A2 SD card. All units have a capacity of 128GB.
Before we show you game loading benchmarks, let’s share the read and write speeds we got when testing the cards in our Steam Deck’s Desktop Mode with KDiskMark, which is more or less CrystalDiskMark but for Linux.
We tested the cards after filling them with games, with the three games taking up almost precisely 100GB of storage space. This made their performance slower than what you’d get by benchmarking empty cards—flash storage gets slower when filled up—but these results are more realistic since you probably plan to fill the SD card with games anyway.
Finally, you can also see the measured performance of the SSD inside our Deck, a 1TB Western Digital WD SN740 unit. Note that the WD SN740 is a PCIe 4.0 NVMe SSD, however, the drive is limited by the Deck’s PCIe 3.0 x4 slot that tops out at 4GBps/4000MBps.
Silicon Power Elite U1 128GB MicroSDXC
This is a budget-oriented SD card that, surprisingly, achieved the highest overall performance despite being the slowest of the bunch, at least on paper.
SanDisk Ultra 128GB U1/A1 MicroSDXC
The SanDisk Ultra is a U1/A1 card, and while it features similar sequential read speeds—the first two rows of the first column—as the other two cards, it’s the slowest concerning sequential write as well as random read and write performance.
Samsung EVO Plus 128GB U3/A2 MicroSDXC
The Samsung EVO Plus is, on paper, the fastest card of the bunch. However, its real-life performance is in the middle, with the affordable Silicon Power card beating it where it matters, in sequential write—the first two rows in the second column—and random read and write performance—last two rows.
Samsung EVO Plus 128GB
The Samsung EVO Plus SD Card is a pretty solid choice for Steam Deck storage expansion.
Western Digital WD SN740 1TB PCIe 4.0 NVMe SSD
Lastly, the PCIe 4.0 NVMe SSD in the form of the WD SN740 is by far the fastest storage device on this test, which was expected.
Steam Deck Internal SSD vs. SD Card Benchmarks
Below you can see loading times for three games: Rollerdrome, Shadow of the Tomb Raider, and Days Gone. The first game is a level-based indie title with undemanding visuals. The second title is a relatively modern semi-open-world AAA game, while Days Gone represents a fully open-world AAA game, which should take the longest to load into.
In Rollerdrome, we loaded into the first level, while in the latter two, we loaded identical autosaves. We’ve also included the Shadow of the Tomb Raider graphical benchmark to test whether any of the three SD cards negatively affects in-game performance. The benchmark used the low preset without anti-aliasing.
Note: We loaded each save/level three times, with the loading times shown on the table being arithmetic means. We also ran the Shadow on the Tomb Raider benchmark three times and calculated the average performance from those three runs. We made sure to fully exit the games between each game load and benchmark run.
As you can see, there’s no significant difference in loading times between the three SD cards. The Samsung EVO Plus SD card took three seconds longer on average to load our Days Gone autosave compared to the other two cards but other than that, the differences between the three SD cards are academic. The good news is that using an SD card didn’t negatively affect Shadow of the Tomb Raider in-game performance.
On the other hand, expectedly, the SSD offers the fastest loading times. You’ll save four or five seconds loading into your Shadow of the Tomb Raider save compared to storing the game on an SD card. Days Gone has bigger gains, but it’s not the end of the world if you wait eight to ten seconds longer for your game to load.
The Results Are In
The results show that using an SD card does increase your game loading times, but not by much. And when it comes to picking the right SD card, a UHS-I U1 SD card is fast enough for your Steam Deck, even for the latest and greatest open-world AAA games.
As long as the card comes with decent sequential read and write speeds of about 90MBps and 50MBps, respectively, and a random read speed of about 12MBps-15MBps, you’re golden.
The pricier A1 and A2 cards aren’t making any considerable difference in loading times, so we don’t recommend buying those unless you can get them for the same price you’d pay for a budget U1 SD card.
With that said, don’t go and buy the card on Amazon. The online marketplace has a long-running problem with counterfeit cards that still isn’t solved. We recommend Best Buy, manufacturer online stores, or other big-name brick-and-mortar places such as Walmart or Target instead.
