How to limit SATA III to SATA II speed on MBP 2011

Question

How to limit SATA III to SATA II speed on MBP 2011

I've bought an 240 GB SSD with SATA III interface. The SATA controller detects the device correctly and sets up a 6Gbit/s connection.

With this set up my system - and according to many public postings many other systems, too - experience temporary failures of the connection, i.e. the system repeatedly stops sending data over the sata connection. Some information hint that the SATA cable doesn't support 6Gbit/s because it's not shielded well.

I would like to solve this issue by limiting the SATA-sped to 3Gbit/s. This should be possible somehow...

Does anybody know how to configure the SATA-controller to set up a SATA II / 3Gbit/s connection to the SSD?

Thanks in advance!

MacBook Pro, Mac OS X (10.7.4)

Posted on Jul 29, 2012 3:07 AM

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Answer 1

Jul 29, 2012 3:17 AM in response to longtimesupport

I doubt that your problems would be solved by trying to get 3Gbs out of a computer that has a SATA III that connects at 6Gbs. What type SSD do you have? While it's possible that it could be the cable, I doubt that's the problem, either. The problem is more likely with the SSD itself or the firmware used with it.

Clinton

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Answer 2

Jul 29, 2012 10:18 AM in response to clintonfrombirmingham

This article (in German) describes a thorough test.

http://www.mactechnews.de/journals/entry/Macbook-pro-2011-und-sata-3-Erfahrung-6 10.html

Another one is

http://forum.hardmac.com/index.php?showtopic=9957

(google for "ssd sata 3 macbook pro 13 2011 hang" and you will find many reports of incompatibilities.)

The author tested one sata II and three sata III solid state drives in an MacBook pro 13" early 2011.

There are many articles in the net describing problems with MBP 2011 and sata III ssds.

I hope that limiting the sata controller to 3Gbit/s will solve the problem.

I would prefer this solution over buying a sata II ssd. First, because all modern ssd have sata III support and second, because I will be able to use the ssd when I switch to the MBP 2012 at some time in the future.

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Answer 3

Shootist007

Level 6

16,709 points

Jul 29, 2012 10:27 AM in response to longtimesupport

This is on the CD/DVD bay port, Right?

Yes the cable used by Apple for the superdrive really isn't meant for fast SDDs. the best thing to do is put that SSD in the main bay and whatever spinning HDD you have in the optical bay.

If you are using 2 SSDs then you may need to get a SATA 2 SSD for the optical bay.

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Answer 4

Jul 29, 2012 10:41 AM in response to Shootist007

Hi Shootist007,

I am not talking about the optical drive bay. I replaced the original (magnetic) harddrive.

Hi clintonfrombirmingham,

the ssd is an Mushkin Chronos 240GB with sandforce controller SF-2281.

The EFI-Firmware ist the most recent for the MBP-model (v2.3).

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Answer 5

Jul 29, 2012 11:13 AM in response to longtimesupport

longtimesupport wrote:

Does anybody know how to configure the SATA-controller to set up a SATA II / 3Gbit/s connection to the SSD?

Thanks in advance!

With what you're planning on doing, you can not configure your sata controller to downgrade to sata 2, (to my knowledge) since you can not access your Macbook's BIOS/CMOS settings.

Your best solution is to purchase a sata 2 SSD which is still available...

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Answer 6

Jul 29, 2012 2:31 PM in response to Bimmer 7 Series

Thanks for this idea:

There is a way to change kernel settings before the OS starts.

The file com.apple.Boot.plist in the directory /Library/Preferences/SystemConfiguration.

Does a manual for this file exist? Are there other way to tell the kernel pre-boot-variables?

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Answer 7

Jul 29, 2012 2:36 PM in response to longtimesupport

No offence - prefer not to give suggestions on something that might mess up your macbook.....

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