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You are here: MacNN Forums > Hardware - Troubleshooting and Discussion > Consumer Hardware & Components > big difference between Sandisk Ultra SD 30 MB/s and 45 MB/s?

big difference between Sandisk Ultra SD 30 MB/s and 45 MB/s?
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Le Flaneur
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Join Date: Oct 1999
Location: Austin, TX 78751
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Jun 20, 2012, 06:51 PM
 
I'm considering two "Ultra" type SD cards from Sandisk: one is rated at 30 MB/s (but doesn't reach that in reality), and there's another sort rated at 45 MB/s.

What I'd like to know is: is the 45 MB/s card appreciably faster than the 30 MB/s card?
     
SierraDragon
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Join Date: Mar 2004
Location: Truckee, CA
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Jun 20, 2012, 08:39 PM
 
FYI my coarse tests of the 2011 17" MBP's EC/34 slot using a $40 SanDisk Extreme Pro Express Card Adapter for CF cards from Amazon:

    -Sandisk Extreme III CF Card, SanDisk EC/34 Adapter = ~10 MB/sec
    -Sandisk Extreme IV CF Card, SanDisk EC/34 Adapter = ~37 MB/sec
    -Sandisk Extreme IV CF Card, SanDisk EC/34 Adapter = ~36 MB/sec

    -Sandisk Extreme Pro CF Card
     (UDMA6), SanDisk EC/34 Adapter = ~80 MB/sec

For comparison, a Sony USB card reader's fastest upload was ~12 MB/sec even with the fast UDMA6 card.

-Allen
     
Le Flaneur  (op)
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Jun 20, 2012, 09:22 PM
 
Unfortunately, I'm interested in SD cards, not CF cards -- inserted in the SD card slot of a MacBook Pro (mid-2010).
     
P
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Location: Gothenburg, Sweden
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Jun 21, 2012, 04:45 AM
 
Common rule of thumb is that you do not feel a speed increase of less than a doubling. Your watch might though, if barely. IIRC, that SD card reader runs over USB, so you will be running up against the USB transfer limits. Theoretical USB 2.0 limit is 60 MB/s, but at least 15% of that is gone in transmission overhead according to USB-IF. What tests I can find show transfers might reach 40 MB/s, maybe, but that is rare. I think the actual difference will be small, but you might notice it.
The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.
     
   
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