I recently purchased a Pentax K3 and started taking RAW images and needed a fast write speed card. i had two 32gb and one 16gb Extreme Pro card i used in my K30, K50 and K-01. I used SDformatter to format the two 32gb cards in my K3, during my first outing at the local zoo, i was not able to view my images shortly after taking pictures, this time got longer and then there was no delay. After i got home, i uploaded the images thru a 3.0 memory card reader. The upload speed started at around 65mbs then almost stopped, then up to 45mbs, then almost stop, then up to 25mbs until all the pictures were transefed. I reformatted the cards and wrote some pictures to the card, it did the same thing. I thought it could be my card reade, so i inserted a Samsung Pro+ card i had and wrote the same picture file, the write speed started immediately at 68mbs and did not vary more than 5mbs. Is this normal for Sandisk Extreme Pro cards?
Hello,
no this is not normal and the speed of the transfer should not go down to 0 and stop but it should be quite the same all the time if the files have a similar size.
so in that case i suggest contacting the support for further invastigation on the issue
Just what i thought, that was really weird for such and expensive top line sd card. Thanks for the reply 
SanDisk is replacing my two 32gb Extreme Pro cards, they are on their was to California
Hello,
this is very good to see and i do hope that the new ones will work fine
I really hope so, i have tried the 64gb lexar pro cards and they are very slow, i missed so many pictures 
The only cards that have worked were the used 64gb samsung pro + cards. I work for a korean company and have first hand experiance on there outlook on quality. They work good , but do not give me the comfort when shooting like Sandisk!
What is the usual turnaround time for getting replacement cards? It has been two weeks since RMA was updated to, replacement shipped!
Hello,
to be honest i do not know the exact time for the rma but i am sure that you received an estimated date in your email with the explanation.
Well they finally shipped my replacement cards today
Well i received my two 32gb Extreme Pro replacement cards today, after formating them using SDformatter, i ran a speed test using ATTODiskBenchmark. Both cards tested the same as the ones i returned, write speeds off 26mbs and 32mbs! Sorry i will not waste anymore of my money on SanDisk products if this is the best they can do 
Hello,
first of all as far as i know the ATTO test is build for HDD/SSDs and not cards. Furthermore sandisk recommends the crystal disk mark software for speed tests
also, before replacing the cards again i would recommend checking if the reader and port are usb 3.0 or 2.0, because if you are testing the cards on a usb 2,0 port or reader then the maximum speed that you can reach will be 45mb/s so the cards are fine.
so, i would test some other factors with the cards to check what could be the cause of the issue
A link to ATTO software was provided by SanDisk Global Costomer Care Department. I am using a usb 3.0 card reader, the card i am using now while waiting for replacements from SanDisk are a Samsung Pro+ and it tests super fast 95mbs read and 89mbs write. These are the only cards that test slow, my SanDisk 16gb Extreme Pro has a read speed off 96mbs and write off 91mbs.
Hello,
if the link was provided directly from sandisk then i would recommend contacting them again to ask what could be the cause of the very slow speed of the card and find the solution since the replacement does not seem to help
Hi
Thank you for you help! I have sent and email to them Saturday, have not gotten a reply yet!
Kim
Hello,
you can also call them directly to speed the process up and receive a reply at once.
here are the numbers
Hi, i just wanted to update this form on how my problem is being handled. I have contacted SanDisk Global Custome Care and was transfered to a Level 3 engineer who first asked all the same questions i provided to the online chat tech. He than blamed the slow speeds on the software i was using, (the software link was provided by SanDisk) and recomended increasing my test file size to 100mb and use Crystal Disk Mark. These test results were almost identical to the ones i got using the ATTO benchmark tool. Now he is blaming the results on mt usb 3.0 card reader, and is sending me a SanDisk card reader.This is all good but does not explane why my camera has extended buffer delays when shooting raw and jpeg files to cards 1 & 2. The supose speed of the SanDisk Extreme Pro cards is why i purchased them and much cheeper brands are preforming better in my camera
