After installing OS X Yosemite on new SSD drive, iMac is experiencing a continuous boot.
1) Tried to boot to safe mode (press shift key) - unsuccessful; stops half-way during boot process.
2) Command+option+P+R - Reset NVRAM.
3) Installed OS X Yosemite on external drive thinking the new SSD had an issue. Get the same result on the external drive when selected as boot disk.
4) Disconnected un-needed peripherals, to include the network line before restart.