SanDisk Extreme PRO 64GB SDXC Memory Card up to 300MB/s

How to obtain Sandisk's posted read speeds
I’ve bought dozens of these Extreme cards over the years (95MB/s, 100MB/s, 170MB/s and now 200MB/s editions), so I know exactly what to expect. But what I didn’t realise until recently is that Sandisk’s SD card speeds are stated much higher than you would typically get, unless you own a very specific SD card reader.

Sandisk’s recent UHS-I (64GB and higher) cards now have “SanDisk QuickFlow Technology” in order to reach these faster speeds. If you do not own a SD card reader with this SanDisk QuickFlow Technology, you will struggle to see consistent speeds much above the standard SD UHS-1 read speeds – approximately 100MB/s (that’s about 90MB/s write speed). It shouldn’t matter what version of USB-C interface is used, since 200MB/s is the same as 1.6Gbps – i.e. still much less than the 5Gbps speed of USB 3.0 (aka 3.2 gen 1) and much less than the 10Gbps of USB 3.2 gen 2. Any USB-3 port should be fast enough.

Sandisk’s Extreme Pro USH-II USB-C reader (previously sold with these cards) does NOT include Quickflow Technology. The Sandisk Professional card readers that do have Quickflow have their own caveats (the one with a CF card slot can reach speeds of 170MB/s, the one without a CF card slot can reach 200MB/s but cannot read the additional pins from UHS-II cards). Google “SanDisk Quickflow Tech Brief” for clarification – because it’s a mess to understand.

I would also state that I’ve always bought my cards shipped by and SOLD BY Amazon. The seller is important – as you will always get the real thing. I would be wary of using any Warehouse versions as you don’t know who the original seller is. These Extreme and Extreme PRO cards have always been prone to fake knockoffs. The prices here also fluctuate a lot, so I always put the desired cards in my wish list and pounce when it drops.

I personally steer away from their Sandisk’s “Ultra” line, simply because I’ve had too many failures – something I’ve never experienced with the “Extreme” products. So the extra is worth it if reliability is a necessity.

I’ve had the luxury of dealing with Sandisk warranty support a few times (typically the SD card becomes ‘locked’ and cannot be formatted properly), and they have always been excellent to deal with. Just take a photograph of the serial number and fill out a form on their website. They usually send back a better card anyway.

Hope that helps.

Addendum: My last order for the 128GB card was made in Malaysia. I found no difference in performance to the previous dozen cards I bought that are made in China. The “Made in Malaysia” indication is underneath the serial number in the same colour/font (instead of “Made in China” being embedded in the plastic).