iMac 17 intel

I switched the hdd but I can't seem to install the os I have a gray screen blank any help appreciated: I can' get the disk out how do you eject? New to imac

how did you copy from old to new HD ?

Old hdd blank I got an os from apple snow lepers

let us make life easier, can you use Carbon copy cloner download from internet ?
use the new drive as external drive copy old drive to the external, test if okay, if it is.
replace the internal drive with new HD, You should be in business.

New hdd

I am not able to copy from old to new hdd I have installed new hdd and am trying to install os but will not boot getting a grayish screen what to do? Did I miss something? My disk is spinning but that's it

Did you hold down the Option key when the chime sounded?

Option key

I held down the option key at the chimes still nada disk is spinning now there is a ? On the screen

Forget about the new drive, is your old drive when used as internal is it bootable and working ?

Had the ram in backwards

Thanks forthe help I am now installing my os so far so good!