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Amethyst

macrumors 6502a
Original poster
Aug 8, 2006
582
210
i have test my mac pro 2013 & imac 5K usb3 external disk performance using same drive (Transcend Storjet 25s3+intel 530 ssd peak (500/550mb)), and i found that mac pro is somewhat slower than iMac as shown in attached image.

is it normal?
 

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kennyman

macrumors 6502
May 4, 2011
279
38
US
Checked the test file size, noticed:

nMP - 512 MB
iMac - 1 GB

I would suggest to run the test again with the same file size.
 
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Amethyst

macrumors 6502a
Original poster
Aug 8, 2006
582
210
just change file size to 1GB, nothing change.
 

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chrfr

macrumors G5
Jul 11, 2009
12,132
5,595
i have test my mac pro 2013 & imac 5K usb3 external disk performance using same drive (Transcend Storjet 25s3+intel 530 ssd peak (500/550mb)), and i found that mac pro is somewhat slower than iMac as shown in attached image.

is it normal?
The 2013 Mac Pro has hardware limitations on USB 3 performance. It's not surprising that the iMac is faster as with that computer, USB 3.0 is integrated into the chipset.
http://macperformanceguide.com/MacPro2013-USB3-performance-limitations.html
http://www.anandtech.com/show/7603/mac-pro-review-late-2013/8
 

Joe The Dragon

macrumors 6502a
Jul 26, 2006
869
257
The mac pro is also at the limits of PCI-E moving usb 3 to the chipset will not help that much as the chipset DMI link is only pci-e 2.0 or 3.0 X4.
 

ActionableMango

macrumors G3
Sep 21, 2010
9,610
6,895
is it normal?

I assume so. I've seen similar results with my 2010 MP and a 2012 Mini. The Mini is a little bit faster.

And I'm even seeing the same difference when using rotational hard drives. There's certainly no bottleneck slower than the rotational hard drive itself, so why is there a speed difference between the two computers? I assume there's something in the Mini's chipset or the CPU itself that lets it handle data transfer more efficiently.
 

mmomega

macrumors demi-god
Dec 30, 2009
3,878
2,085
DFW, TX
Interesting though.
I'd like to test this myself across a few different Macs of various years.
 

ColdCase

macrumors 68040
Feb 10, 2008
3,164
203
NH
Latency and HD cache affects USB protocol in unexpected ways. So a rotational drive could performs differently from one host USB implementation to another. Its more than the number of bits than can be pushed through the pipe as the drive may write and acknowledge which can have some variations.
 
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