How to replace my original SSD iMac 2011

[Amu]

My iMac mid 2011 was build with 256 SSD (3Gbs) and 2 TB HDD (3Gbs).
Now I like to upgrade the SSD 256 3Gbs with the faster SSD 512 6Gbs
Because the Bus is a 6Gbs SSD and HDD.
On not one place I find where this SSD is located in this iMac just how to upgrade them.
When I call Apple service to do the work for me the told me the not swap with other not tested SSD drives?
This mean I do it myself.
Before I start I like to know where is this disk exact located and is any SSD possible to work with this iMac.
The SSD I going to install is the Samsung SSD Pro 512.
If you know what disk I can install in the place of the 2TB HDD aim happy to also get this information, because I know not any HHD can work with iMac. The fan is getting info from the HHD.
Thanks to all if you can help my out.
Marc

 

[dilgit]

try

 

[fleshkopter]

I just did exactly this, twice actually. The original apple installed ssd is directly behind the optical drive and is mounted with 2 metal brackets, 4 screws hold them onto ssd, and 3 screws hold the whole thing onto the imac. Much better than the adhesive method that OWC suggests. Anyway, I moved my original apple ssd to the optical bay using OWC data doubler since i never use the superdrive. I first put a 512 GB Samsung 840 EVO ssd in the original ssd location behind the newly relocated apple ssd. I had problems with the samsung, it hung sometimes and also it thought the power was unexpectedly cut off whenever I put the computer to sleep. That Samsung ssd is going back to amazon, I replaced it with a Crucial m55O after macthefork reported success with that brand. So far, working great, no power failure hallucinations when I sleep or restart the comp, and TRIM is enabled. I would recommend this brand/model. The only tricky part of the install is taking the lcd panel out but it's not that bad. Get the right tools from OWC. You do not need adhesive or a new SATA cable, the existing one apple installed works just fine. Oh yeah, the original apple ssd is quite happy in the optical bay, working as well as ever.
scroll to the bottom of this page for pictures of what you will see.
http://www.macworld.com/article/1160311/ssdimac2011.html