Yosemite on SSD boots from USB but not when the SSD is installed internally In another thread I have explained the issues I have with a clean install of OS X on a SSD.

Now the situation is:


Yosemite installed on SSD.
Boots from SSD attached via USB .
Does not boot from SSD when installed internally.
I get a beachball and the Mac will not start.


What might the problem be?
Just because the hardware is set to remember where the last boot was from and will look back to it at the bext boot, I can recommend you to hold down the C button right after you start up the fully assembled system and then select the SSD again. 

Also note that the cable that connects the internally placed SSD may be damaged/disconnected somehow or even the Motherboard could have a problematic/defected chip.