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-   -   SD card performance/recommendations (http://www.anythingbutipod.com/forum/showthread.php?t=72948)

kp-j3 10-20-2013 12:23 PM

SD card performance/recommendations
I use SD cards in my car stereo, and one of my SD cards is extremely slow. Using a benchmarking tool http://www.attotech.com/disk-benchmark/ I found that it's maxing out at 15MBs write, and 20MBs read. All of the other ones I've tested are hovering around 80/90. The strange thing is I have 2 Transcend SDXC 64GB class 10s that are supposedly identical, and one's the dud, and another blazes almost as good as a sandisk.

Anyone have any recommendations on achieving higher speeds without randomly buying cards and hoping for the best?

I see this one:

But I'm certainly not paying $600 for a 64GB card. (claimed 400MBs/1200x)

Even this one is $225:

but I'm already achieving neer that speed with every other card I've bought for ~$1 per GB, except for the one outlier.

Good cards take ~16 seconds to scan the file system and rebuild the database, the crappy one takes 34 seconds, and the system boot time is an additional 11 seconds.

Just Some Guy 10-20-2013 02:09 PM

Are all those write speeds really necessary to what you're doing with them? I ask because unless you're constantly moving files around with them (which is supposed to be bad for SD cards, as they have a limit on the number of times they can be read/written), I don't see how it would make that big a difference.

I could see if you were a spy, and needed to get all those secret files off of the bad guys computer as quickly as possible, then that write speed would be handy...

kp-j3 10-20-2013 02:59 PM

Write speed isn't a big deal. It's more read speed that I'm worried about. But they seem to be nearly the same based on the limited testing I've done.

steinburger1109 10-22-2013 12:18 PM

Out of curiosity, what are you doing that you need read speeds higher than 20MBPS? As far as consistency in the "identical" cards, all class 10 guarantees is read/write speeds higher than 10MBPS so, technically they both work as advertised, it may just be one has been used more and is degrading, there may be manufacturing differences, really just a plethora of reasons they could act differently.

But to my first question, 20MBPS read times are more than enough for any kind of music or video playing really, which is why I'm curious about what you're using it for :p though at the same time, my class 4 reads around 20, so I would have expected a 10 to be at least more than that.

kp-j3 10-22-2013 05:44 PM

Nothing special really.

I was just hoping if I could get a not unreasonable cost card that was faster, the light off time would drop. I'm sure there's a limit to the read speed capacity of the head units, and I may already be there.

Was just wondering if anyone had come across some really good measured speed vs. cost in their pursuits.

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