I thought id post a thread on this - and possibly re-write it later on as a resource for anyone looking to mod their 2011 iMac as the modification thread is full of untruths, lies and people thinking they're right but have actual misunderstood the situation. This makes it very difficult for anyone trying to carry out any mods to their 2011 when they can't tell which is the right answer. First of all I've got the 3.4ghz i7 27" Mid 2011 iMac. Ive fitted 16gb of ram (you can go up to 32gb but even I considered that overkill at present especially with a price performance stake) Ive got the Amd Radeon with 2gb of ram on it so its pretty maxed out at stock. Ive since fitted 2x Vertex 3 MAX IOPS (thats the level up from the standard Vertex 3 drive the enterprise version if you wish which much faster random 4k times) on the two sata 3 buses running raid 0 and put a 3tb drive in place of the original drive. This enables my system disk to run at a read and write of 1000mbps. I previously had a 2009 iMac with two Intel X-25m G2's fitted in it running again raid 0 and I can safely say for day to day activity this computer is even snappier and faster than that. Ok - so for anyone with even a basic competence in electronics opening the iMac is not difficult at all. There are people in the thread saying its scary, really difficult, they broke stuff. Im not sure how they broke stuff. If anyones ever built a PC opening the iMac is slightly fiddlier but no more difficult. I would say due to the size taking apart and putting back together an iPhone is much more difficult. All the connectors come off the motherboard very easily and they're all uniquely shaped (even the speaker ones, one is 5 pin one is 4) so you can't go wrong plugging them back in. I took the logic board out and flipped it over to get a good look at the sata ports. Apple have decided to allow Sata 3 on the port the original hard drive is on (that can't make use of it) and on the spare SSD socket. The middle socket which is for the optical drive is only sata 2. Obviously we want to get our hard drive running on this bus and save the 6gbps sata ports for the SSD's. This is the trickiest bit as it requires some cable modification (although not difficult) as Apple has done this They have a propriety connector for the power for the hard drive. You have to use this to power any 3.5" hard drive you put in as it carrys the correct voltage, the other two are slimline sata ports and will only power an SSD (or an optical drive) Much ridiculous fuss has been made (and plenty of scaremongering articles) of Apples power cable and the inbuilt fan system. ITS REALLY SIMPLE. You can do one of two things. The power cable conveniently has 7 wires for each pin, you can cut wires 2 and 7 and short them together - this is what Apple do when you only have an SSD fitted and no hard drive with a connector on the logic board. Or you can use a Sata power splitter which also shorts pins 2+7 and use of the plugs to go into your new drive (leaving the other spare) Thats it no fan issues. Its really that simple. The sensor is now off. Ive fitted a low power green drive (you don't have much choice with 3tb drives anyway) which doesn't create any heat. Either way I bought the SMART OSX program which monitors the hard drives SMART stats (the same way every other computer in the world does) and sets the fan to the correct speed to keep it cool. I did a 24 hour stress test on the drive copying files to it and monitored, the heat never rose enough for the fans to go over 1300rpm. Its perfectly safe to have this fan stay at its 1000rpm it'll run at now, the heat inside the case is fine and anyone worrying about that is again, mistaken fool. I ripped out the optical drive. I mean really. Its 2012 folks, why on earth you'd want an optical drive wasting space inside of your powerful iMac I don't know. There is nothing super about the super drive. I haven't used optical media at all since 2003, but even if you do get a USB drive - the speed of these things is so slow why on earth would you waste a valuable Sata bus on an optical drive??? The mind boggles that people would rather cripple their hard drives by having them run on USB or Firewire externally whilst keeping an optical drive inside their computer that will run perfectly well on the rare occasional they use it over USB. Rip that bastard out now and put something useful in its place! In my case the hard drive ran on that bus - but I had to take a junior hacksaw to my slimline sata to sata cable. Why? Because I needed the power from the original sata port for the drive and I needed the data from the second sata power which is a slimline sata connector on the logic board. Hard to explain in words - easy when you see it in pictures (they're coming) You basically have to take the power from one port and the data from another to have the hard drive use the slower port. You can then take the data from port one and the power from port 2 for your first SSD and the final spare port is a simple Slimline Sata to Sata cable straight to your SSD. I could have spent an extra £70 ($130ish) or more on an optibay and the Apple SSD mounting part for a really neat job but to be honest its not necessary for SSD's. Its like paying to mount your USB stick with no moving parts inside of a fancy hand bag. SSD's will sit anywhere - so I popped them on top of each other in the space for the optical drive and stuck them there with 3m tape. They don't generate any heat what so ever, but I left the optical fan connected anyway. I probably could have safety removed this an reduced the iMac to 2 fans but I left it active and now cold air blows out of the optical drive slot on the side of the case. Infact with the optical drive removed and the hard drive sensor running at only 1000rpm the whole system is general a few degrees cooler than it was at stock! Figure that out (less power draw from my new hard drive, optical drive removal allows for better air flow and SSD's draw little to now power and make no heat) Sticking the thing back together was a breeze and it booted first time as id CCC'ed my old OSX over onto the 3tb drive before starting and it picked it up straight away. I then set up my SSD's and raid array, cloned the operating system over to them and rebooted hey presto job done. Everything runs so smooth and fast it makes my heart happy. Working in Final Cup Pro X is like working in real time just grabbing any video from anywhere you want and instantly scrolling through it all. Every single tasks the system does is snappy I love the small file performance of these drives I'm super happy. If anyone is stuck on any part of this procedure just drop me a PM and if anyone in the UK wants me to do it for them again send me a PM, I realise its a specialised job for this level of customisation but seriously this iMac is going to be screaming faster than any stock iMac for 2-3 years to come. I'll probably be able to stick a 4tb drive in at some point, maybe even upgrade the SSD's slightly - 32gb of ram will also be an option at some point and of course with the thunderbolt port at 10gbps there is no reason I couldn't attach an external SSD that saturates that and possible achieve 2000mbps speeds in the future with a 3 disk raid-0 array and possible a nice 500gb of storage at that speed. Im glad I moved up from the 2009 iMac as it didn't have this kind of expansion potential.