High Speed SD Cards


Senior Editor
Staff member
Okay, so SD cards are not that exciting, but I take a fair few photos and it's kinda painful to wait forever to transfer files back and forth from the damn cards. So, I thought I'd get a faster card and was kind of surprised to see a 95MB/s SD card by SanDisk (Extreme Pro). There was me thinking no way it's that fast, and to some extent, I was right. That 95MB/s is decimal transfer speeds, not binary. I've known about storage using decimal bits for a while, that's why a 1TB drive is actually 931GB in the OS since the storage is declared as 1000 bytes per kilobyte instead of 1024 (binary) - as reported by the OS. But now companies are reporting speeds in decimal too, so that 95MB/s is actually 92.7MB/s. OK, still damn fast, but is it really?

I saw some of the reviews saying it was fast and all, but no real benches ( that I saw at the time). I bought the card anyway, plugged it in, and saw lightning fast times of 20MB/s. Wait, what? Oh, right, yeah... kinda forgot the whole USB2.0 thing being limited to about 35MB/s minus overhead. So I bought a USB3 card reader too (Kingston if you must know). It arrived, it was installed, then I ran CrystalDiskMark. Well what do ya' know...

Th SD card was an 8GB card formatted to FAT32, default 4K sectors. This is the Crystal default test of 3x runs with 1GB transfer. Good test for HD video recording.


This is 5 runs at 50MB transfer. Does seem that it handles smaller file bursts better - suited to RAW photos.


Surprisingly, it handled rather well. Ok, so the write speed isn't quite up to par, but there can be numerous reasons for that - from the card reader, interference, cable and even the controller. But it definitely shows some rather insane speeds from a humble little SD card. So yes, high-speed SD cards exist, you just need a camera that can support them and a USB3 card reader.
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Partition Master
declared as 1000 bits per byte instead of 1024 (binary)
You mean 1000 Bytes per Kilobyte (oops) etc and so on right? Since well you know its 8 bits per Byte. Which is the whole reason why the metric has always been 1024, multiples of 8. Yeah between advertising departments and formatting, storage has always been a bit lacking :p

But why do people complain now? I mean the complaints are 20 years behind. Were they not complaining when 1.44 MB floppies only held 1.38 MB (Though I now read they were 2.0MB unformatted wait what?)? Its that silly bit of math where the percentage of available storage doesn't change the more storage you have the more you lose formatted. Adding in the advertising departments technical dependencies doesn't do too much worse.

You have had me curious how my old card stands up. SanDisk Extreme III 4GB Class 6.


I used a SanDisk USB 2 reader I had laying around. These tests were over the USB 3 on the motherboard. The native USB 2 was a bit slower. Which finally settles a debate I have been having!

Luckily my D60 couldn't out shoot any decent standard card. The Ultra II's and Extreme III's of the day were overkill but i buy them anyways.
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Senior Editor
Staff member
Schoolboy failure... I knew I shouldn't have posted that when I was tired! Fixed now though, 1000 bits, sheesh... it's 1000 bytes per kilobyte, instead of 1024 (not megabyte there :p). Anyway...

The speeds you're getting there are exactly the same as what this card got through both my monitor and through another USB 2 card reader. Seems to be the limit of USB 2. I don't know how people got close to 30MB/s but oh well. So there is a good chance you could go faster over a real USB 3 device - it's just whether you need the extra speed or not.

Ohhhh - hold on a sec, I have the exact same card in my camera at the moment, let me burn through a couple of benchmarks with it then over USB 3.

Well, they're faster, but also slower, compared to your results. Something tells me I have some kind of artifact in the loop, bad controller maybe? Who knows. Anyway, RESULTS!

3 pass 1GB transfer.


5 pass 50MB transfer.

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