Original post by: glen street ,
iMac 27" would boot to white screen. I had added a new HD to the main position and put an SDD drive in the CD rom Bay. The computer would not recognize either drive. After 5 to 10 minutes, I would get a Dos page only with no bootable drives. and to proceed to Recovery of Wndows. I would hit enter and the next screen would list the MacDrive and the Windows drive. If you clicked on the Windows folder it would immediately boot to the Windows platform. I had a complete use of the windows system on my iMac. Question was why couldn't I boot to a Mac OS. Further along I removed both drives and with a plug in USB keyboard started the iMac, this time I got a folder. "this means no HD on the computer, working This is the first time I had gotten a folder other than the white screen. I thought this is progress. I immediately used my USB external drive and rebooted, this time I got the folders from the option Key startup. This is the first time it had happened in months. I hooked up the main drive cable and did a boot to recovery, then a disk utiliy, from the Recovery menu and a new install on the Main HD of the iMac 27". I now have a working Mac OS. Before I got this computer someone had used Bootcamp on the original HD, which had gotten corrupted, from there it would only Boot to white screen.