27" iMac won't boot past white screen.

Is your i-mac still operating properly after the video card was replaced?

Following the advise before my post, I removed all connections from the back of my Mac, including power. In 30 seconds I reattached the power cord and it booted right up. I then reattached all connections and it is fine.

I have now installed the operating system on a flash drive and the problem remains. I am sure it is not a video card issue as I can sometimes boot up in Safe Mode and the picture while slow seems to look fine. None of the above have worked for me.

This just happened to me today. I had no other devices plugged in so I just pressed the power button off and unplugged it for a minute then plugged it back in and it worked. Just a few moments of sheer panic when I thought I had lost all my stuff! If you ever watch the "I.T. CROWD" their advice is always my go to...."turn it on and turn it off again." Works more than it should but I'm so glad that it does!

I have tried every single method since the very first post.
None of them worked for me so far.
My 24´ iMac does not pass through that evil white screen! I have made it through to the disk utility once, done the repair and the report came out ok, but after a reboot, the problem was still there.

Is this a disk malfunction or a graphic card problem?

One of the times the system reached the desktop image and I has able to see the folders and files on the desktop, but after a minute or so, it freezed completely.

Not a good day, today...

Thank you!!!!!

Just had this happen this morning - there was some kind of power blip and my computer equipment shut off. When I rebooted iMac, I got the black Apple on white screen, and then just white screen. This power button trick fixed it right up.

Thanks, unplugged everything then it booter