What Mac Pro's support 6 gb/s hd speeds

blunti

macrumors 6502a
Mar 15, 2011
527
15
by default? none. there are a few topics about 3rd party add-on cards though. might wanna check those out...


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derbothaus

macrumors 601
Jul 17, 2010
4,060
4
PCI these day's runs from 2Gb/s to 128Gb/s. So yes if drivers are up to snuff and you slot it correctly there is no problem getting 6Gb/s.
 

FireWire2

macrumors 6502
Oct 12, 2008
363
6
Technically, there is.

Most of the 2x ports SATA 6Gb/s has a design flaw, it has 2x 6Gb ports but connected to 1x lane PCI e V2 (5Gb/s)

It's bandwidth not even 1/2 of what it supports.

It's strange!
 

derbothaus

macrumors 601
Jul 17, 2010
4,060
4
Good point. Watch what you buy. I have never looked for an expansion card in these "modern" times. I think some of the 4x cards go by the name "True SATA 6Gb/s" or "True SATA 3".
 

nanofrog

macrumors G4
May 6, 2008
11,719
2
Technically, there is.

Most of the 2x ports SATA 6Gb/s has a design flaw, it has 2x 6Gb ports but connected to 1x lane PCI e V2 (5Gb/s)

It's bandwidth not even 1/2 of what it supports.

It's strange!
It's a design compromise to keep it cheap as well as minimize the lane usage (i.e. no 2x lane configurations).

So it's either 1x or 4x lanes depending on the requirement; inexpensive vs. performance (that can't utilize all of the bandwidth assigned to it for 2x ports). Most of the 4x lane versions however are 4x port, and there's still a performance limit for simultaneous usage and disks that can exceed the band limitations.

They've waited for PCIe 3.0 to "fix" the issue (1GB/s per lane), and even then, 2x ports running simultaneously still get throttled if the disks can actually exceed 500MB/s for sustained throughputs (still 2x ports on 1x lane SATA controllers). Not a big change on the surface, but if a single disk is run, at least they can operate at full band for SATA III (get the additional 40 - 50MB/s out of the disk).
 
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xgman

macrumors 601
Aug 6, 2007
4,848
652
Note that "boot" support for the sata 3 cards is kind of dicey right now.
 
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