SanDisk Ultra SD Cards aren't as good anymore

Started Oct 5, 2013 | Discussions thread
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Kerusker Senior Member • Posts: 1,199
SanDisk Ultra SD Cards aren't as good anymore

End of last year I've bought two SanDisk Ultra 16GB SDHC cards, which are UHS-I compatible. I also have a SanDisk Extreme 16GB (45MB/sec) card. I didn't find much difference between the Ultra and Extreme except price (Ultra being much cheaper).

Then late August this year I bought a SanDisk Ultra 32GB and used it immediately in my K-5 II on my trip to Ibiza. I got the impression, that the 32GB card was slower in writing than the 16GB ones.

In the following I only write about the SanDisk Ultra SDHC (UHS-I) cards except otherwise noted.

Back home I checked the write speed using the SD card slot of my Sony VAIO F11 with a huge video file. After transfer buffers were filled, I could read out the write speeds of the cards:

16GB: 19MB/sec and 32GB: only 9MB/sec !

I contacted SanDisk about that and was asked to check the cards with ATTO Disk Benchmark:

To my surprise, ATTO gave the same results on my VAIO and Sandisk's statement was 'looks good'.

Huh? Looks good?

I got me another 32GB card - same result (returned it); got me another two 16GB cards hoping for fast 19GB/sec. But ATTO showed only 9 to 10GB/sec - the same as for the 32GB card.

My disappointment is huge because this means that SanDisk is selling products with the exact same packaging with exact the same specs but worse performance in the products life cycle.

Why do I post in this forum?

One of the weaker points of the K-5 bodies is the write speed of it's SD card slot. It's maximum write speed is about 20MB/sec. The slot isn't UHS (Ultra High Speed) compatible. Therefore it doesn't make sense to buy SanDisk Extreme cards for a K-5 or K-5 II.

A UHS-I card usually falls back to a 133x card on a non UHS-I compatible card slot. SanDisk Ultra cards have 30MB/sec (= 200x) read speed which gives 19MB/sec (= 133x) read speed on a standard SD card slot. My Ultra 16GB from last year do nearly write as fast as they read on a standard SD card slot (write 19MB/sec, read 20MB/sec) whereas the newer cards only write half as fast (9MB/sec).

BTW: On my Olympus XZ10 (which has a UHS-I compatible card slot), the newer Ultra cards also are about half as fast in writing than the older Ultra cards.

The upcoming K-3 hopefully features a UHS-I compatible card slot (or two). 

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 Kerusker's gear list:Kerusker's gear list
Pentax K-5 II Sony RX10 IV Pentax smc DA 15mm F4 ED AL Limited Pentax smc DA* 16-50mm F2.8 ED AL (IF) SDM Pentax smc DA 55-300mm F4.0-5.8 ED
Olympus Stylus XZ-10 Pentax K-5 Pentax K-5 II
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