This is not, unfortunately, true of all such drives. Some require setting a jumper on the rear of the drive, while others require a firmware modification that usually can only be done on a Windows machine. If you are going to buy a SATA 6.0 Gb/s drive you had best do some due diligence first. You would be far better off just buying a SATA 3.0 Gb/s drive that will be fully compatible.
Understand, there is no such thing as SATA6.
There is SATA III / SATA3
The channel interface on the controllers support 3.0Gbps (bit)
Only an SSD would even show any difference.
Vendors cannot afford to make drives that are only SATA3, they are all backward compatible.
For speed, high density/capacity can equal faster transfer speeds.
For lowest latency and I/Os per secord or IOPS then SSD are king.
For a little of each and a touch of SCSI class but at t he cost of some noise (and my WD Black 1TBs "chatter" for sure just as much if not more), there are WD 10K VelociRaptors (180MB/sec read/write).
It is almost unhead of to need to set a jumper on an SATA device. SAS/SCSI maybe.
With SSDs there can be and usually are firmware issues with the controllers used (inside the device).
If you MUST get 6.0Gbps (550MB/sec) people buy PCIe SATA3 controllers and get into SSDs on a card even.
Please, what is the answer now to Kakky's original question?
Yes, it can be done, but there might be problems?
No, the «interface» (does that mean the connector?) is different?
Or: does it make sense at all or will the benefit be lost, as stated (unclearly) above?
Could an added kind of card help to fix problems?
Can I use a [6Gbits/sec SATA-3] drive in a 2009 Mac-Pro
Executive summary: Most regular commercially-available drives you buy new today will install and work fine. It IS worthwhile to pay extra for a drive with a bigger buffer, but do not pay EXTRA for SATA-3 alone, it is all specsmanship.
If you buy a weird older drive, or you have a really old Mac, it may not work properly. [WD Raptors and VelociRaptors work fine.]
RE: SATA Bus speed:
Rotating drives available today, whatever their SATA spec, can source data off the spinning platters no faster than about 125MBytes/sec.
SATA 3 is rated at 6G bits/sec, which theoretically is about 750 Mega Bytes/sec
SATA 2 is rated at 3G bits/sec, which is theoretically about 375 Mega Bytes/sec
SATA 1 is rated at 1.5G bits/sec, which is theoretically about 187.5 Meg Bytes/sec
None of the SATA Busses is a bottleneck for consumer Rotating drives you can buy today. Trying to speed up the SATA Bus will not provide any real-world performance increases for Rotating Drives.
Even most common SSD drives are not bottlenecked by SATA 2.
If you put the drives on a PCIe card, they are not bottlenecked by the SATA on the card either, as it will typically be SATA 3.
But unless you have the very fastest SATA drives available, you are in no danger of having the existing main SATA 2 Bus in your Mac Pro slow you down. The card is only needed for the fastest SSD drives available today, and will not provide much current speed improvement even in that case.