Your document is made for adding an additional SSD drive on a mid 2010 iMac i7. id 11.3
1. There was one more screw, or 9 instead of 8 on the motherboard.
2. Sugestions: When you unscrew the screws on the motherboard, as sure to have inserted into the holes at the rear of the frame cable or USB or Firewire to maintain enlignement motherboard during reassembly.
3. enlignement motherboard is very important. Do not neglect the position of either side of the cable and also on the side of your RAM as I disassemble the computer a second time to replace the RAM side of the card.
4. I highly suggest you have good lighting and a magnifying glass if you have eyes like mine. If you are alone, try a frame with magnifying glass and light as jewelers that will secure you.
Note: My experience was a bit complicated because I saw close is not good .with small connectors are difficult to see the male and female to withdraw. I ripped the male and female connector on the motherboard and the two pins on the motherboard broke. I have not been able to restore power as it was the last power button.
Two solutions: Buy a new Imac or cut the connector, strip the son and the son soldered directly onto the motherboard with a distance of 1mm between the terminals. My son helped me because his eyesight and manual dexterity is better than mine at his age.
welding we have succeeded on the motherboard and the computer is left like new. What experience! Later I added 32GB of RAM on a mid 2010 iMac i7 id11,3 is considered maximum 16GB. Now the computer everything is fine.
Nylon Tipped Tweezers
iFixit Opening Tool
iMac Intel 27" Mid 2010 Dual Hard Drive Kit