How to change the Interface Speed of your HGST Hard Drive
from SATA-III (6 Gigabit) to SATA-II (3 Gigabit)

The purpose of this web page is to provide instructions on how to drop down the interface speed of an HGST SATA-III (6 Gigabit / 6Gbps) hard drive to SATA-II (3Gigabit / 3Gbps) so that it can be successfully utilized in an OptiBay installed inside their Early or Late 2011 MacBook Pro. This utility was created by HGST and only works on HGST drives! Do not use on drives from other manufacturers as your best case result will be that it just didn't work and your worst case result will be that you just bricked your drive. Feel free to pose any questions you may have to us at

BACKGROUND: A few months after the release of the Early 2011 MacBook Pro, Apple quietly changed the top speed of the optical bay SATA port, to which the SuperDrive (DVD Drive) is connected, from SATA-II (3 Gigabit, 3Gb/s) to SATA-III (6 Gigabit, 6Gb/s). The SuperDrive connects there at SATA-I (1.5 Gigabit) speed and Apple designed the corresponding SATA circuitry to accommodate that speed as they never imagined customers would remove the SuperDrive in order to install a high performance storage device in that location. As a result, only SATA-I and SATA-II (3 Gigabit) devices function there reliably and SATA-III devices, such as the newer 9.5mm 1TB/7200RPM and 1.5TB/5400RPM hard drives from HGST which we are addressing on this page, as well as hybrid drives, and Solid State Drives (SSDs), do not. Symptoms include: beachballing, system freezes, excruciatingly slow data transfers, and sometimes the device may not even be recognized by the system at all.

VERIFY: To check if your Early or Late 2011 MacBook Pro has a SATA-III optical bay SATA port, hold down the option key on your keyboard while going to the Apple Menu at the upper left of your screen and select the first item there which should say "System Information". Then select, depending on your Mac OS, either "Serial-ATA" or "SATA/SATA Express" and there you will see on the right pane two Intel 6 Series Chipsets listed. While the top chipset normally corresponds to the main drive bay and the lower one to the optical drive bay check to see that in the information below that the "Link Speed" for both chipsets indicates "6 Gigabit." If so, then your machine has a SATA-III (6 Gigabit) optical bay SATA port.

Will this procedure slow down my drive? Great question. The answer is "no". The reason is that the current maximum data transfer rate of these hard drives that can be sustained, that is, when the read/write head is actually reading or writing data to the platters on the drive, is about 160MB/s. SATA-II (3 Gigabit / 3Gbps) is capable of 300MB/s so the drive is barely reaching half of the bandwidth that even the SATA-II interface can provide... And that is at Maximum Throughput i.e when the data being read, or written, is at the outer edges of the platters where the velocity is greatest. The rest of your data sits on inner "rings" of the platters and so is read and written to at lesser speeds.

But can't the on-board cache of these drives burst at the full interface speed? As for the 32MB cache on these drives yes, they can burst at the full speed of the interface but even in the best case senario in which the data your computer requests is taking up the full space of the cache (which is a rarity), those 32MB would take about .05 seconds to transfer at SATA-III (6 Gigabit) and the same 32MB would take about 0.1 seconds to transfer at SATA-II (3 Gigabit) speeds for a difference of .05 seconds. This is a singular event (until the cache fills back up waiting for the next cache "hit" which may, or may not be, anytime soon) which means that once this happens you go back to relying on the sustained transfer rate again which we know already is well within the speed capabilities of SATA-II. That said, then you are taking a maximum one time hit of .05 seconds. If you can perceive this .05 seconds, and this lost time bothers you, then you may be on the wrong planet.

Why do these drives ship with SATA-III (6 Gigabit) interfaces then, if SATA-II (3 Gigabit) is almost double what they are capable of already? It's one of two things. Either the SATA-III chipsets they use on these drives came down in price dramatically, or it's a marketing ploy and it just sounds "sexier" to say it has a SATA-III interface. We think it's likely a combination of the two.

Update: We have since introduced our OptiBay Extreme which contains specialized electronics to allow SATA-III drives such as those from HGST, Western Digital, and Seagate, as well as Hybrid Drives and SSDs to be used successfully in affected machines at full SATA-III speed.


The utility provided in the instructions below is a Windows/DOS utility that you run from a DOS bootable CD that you will make.  (You don't need to have Windows in your system.)  After you make the CD you will need to temporarily install your SuperDrive (DVD drive) into your MacBook Pro, if it's not there already, and install the HGST drive momentarily into your main drive bay, as the CD will only boot the machine when run from an internal SuperDrive.  The speed change only takes a couple of minutes to run and then you can install the HGST drive into the OptiBay and in place of the SuperDrive, and your main drive back into the main drive bay.

1) Here is the disk image as a zip file.  First unzip it then use Disk Utility to burn this .iso image to a CD.  

2) Make sure your SuperDrive is installed internally in your MacBook Pro and put the HGST drive into the main drive bay.  

3) Turn on your MacBook Pro while holding down the option key and quickly insert the disc you made into your SuperDrive.  Don't let go of the option key until you see the disc icon on the screen with the word Windows under it.  Click on the arrow below it and your system will boot into DOS and it will automatically run the utility program.  

4) It should then show the HGST drive and it will indicate that the drive is setup for 6Gbps speed and you can then select F3 to change it to 3Gbps.  It will ask if you are sure and select y.  Then it will say to turn off the machine to finalize the setup.  

5) Hit your Esc key at this point, you'll see some DOS timeout messages which are normal, and then turn off the machine by holding down the power button.

6) Start it up again holding down the option key and select the Windows disc again and just verify that the drive is now showing as 3Gbps.  

7) Then hit Esc and power down the machine once the DOS timeout messages stop.

Now you are all set. Install the drive back into the OptiBay and your main drive back into the main drive bay and you will be able to use the drive without issue now that it's set to SATA-II (3 Gigabit).

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