Blank Screen on Start Up

My aging iMac running 10.6.8 won’t boot past a white screen. I have tried starting in Safe Mode but that doesn’t work, just a blank white screen. I have tried booting from a bootable clone (Super Duper) but it won’t see that either. Even tried the installation disc but that is not recognised either. I’m getting desparate. Any ideas, please?

Just how old are we talking here?

Does it get past the boot selector? Where you can select which drive you want to boot from?

Things to try:

  • Target disk mode
  • single user mode
  • recovery mode (may or may not be available on your machine)

Otherwise, PRAM and SMC resets are always worth a shot if you have nothing to lose.

Thanks Benny. I was a bit short on details, it was late and I wanted to get to bed. It is a 2007 iMac 17 inch, with an upgraded 1 TB Hard Disc. No matter what key combination I try on start I only get a white screen, not options are displayed. I will try it again this morning after it has been disconnected from the power overnight. I might try booting into Target mode using and old MBP. I think I have a firewire cable somewhere. I tried a PRAM reset but still the same results, blank white screen.
Anyway, thanks for your thoughts, any help is welcome.

I’ve seen a few of these where the machine is fine and boots up OK, it’s just a display/display cable/graphics card issue that hides the fact that the machine underneath is fine. If you’ve got the right adapters, maybe try an external display as well, but otherwise Target disk mode will tell you and at least you’ll be able to get your data off that way.

Good luck!

After being disconnected from power overnight it started up this morning, albeit very slowly. So that is good news. I think we will be getting a new iMac in the New Year.
I also confirmed that my weekly Super Duper back up of the said iMac will run on my old MBP so we have that as second string until we get a new iMac.
Thanks for your suggestions, it is always good to be able to talk about these things with knowledgeable people.

I discovered the Time Machine HD had failed. After disconnecting it the iMac started up normally and is running fine. Now for a new Time Machine HD instead of a new iMac.