iMac Mid 2011 SATA Speed limited to 3 Gigabit

[Nesha]

Recently i have installed SSD from OWC - Mercury Electra 6G SSD

I was expecting speeds about 500 MB/s
but here is what i got instead:

Here is what i have in system info:

All is declared to 6 Gigabit but somehow i still heve 3 Gigabit speed.

I saw on some links that i should upgrade firmware with this:

http://support.apple.com/kb/DL1380?viewlocale=en_US&locale=en_US

but when i try to run this firmware i receive msg: "This software is not supported on your system."

Please advice me is there any fix that i can apply to get 6 Gigabit instead of 3 ?

 

[simsaladimbamba]

You can use the following applications to benchmark the speed of your SSD, to see, if BMST is reporting correctly.

• AJA System Test
  
• Xbench

 

[Nesha]

Here is Xbench output

For some reason i am not able to test using AJA System Test, it does not let me to select my SSD (only my old HDD), also video card is not listed :

Also here is what i found about my iMac model:
*As shipped, these models only supported the 3 Gb/s Serial ATA 2.0 standard for both a 3.5" hard drive and a 2.5" SSD. However, as first discovered by site sponsor OWC, the iMac EFI Update 1.6, released two days later, quietly provided 6 Gb/s Serial ATA 3.0 support.

source:

http://www.everymac.com/systems/apple/imac/specs/imac-core-i5-3.1-27-inch-aluminum-mid-2011-thunderbolt-specs.html

 

[Nesha]

I got great support from OWC and here is my result with QuickBench software. I guess it was only problem how i measured speed

I have great speed up in boot time from 1 min and 18 sec to only 25 sec, so i guess that's it

Regards