Screen dies under boot - everything else works

[littlefever]

Im having a strange problem that i cant find alike on google - sorry if theres a thread already covering this problem?

When i boot my iMac 24" (november 2008 - that about all the specs i can give for now) The apple logo and wheel comes on like always - the wheel is turning and everything seems fine - But the wheel animation stops and the screen "freeze" on this image, even tough the system keeps loading and works fine - pressing play on the keyboard two times make iTunes burst with music!

So, it seems its the shift between the load screen and contact to the system that somehow just isnt happening - i didnt install, update or in anyway alter the system the last time i shut down...

I´ve tried div. bootmodes without any success - i can run the iMac in target disc mode and everything on the disk looks fine.

Two things remains for me to try yet - try a secondary screen after complete bootup - try to reinstall system if the first option works (rather wait and hear if anyone has a solution)

Any suggestions for troubleshooting?

Thanks

 

[Macman45]

It sounds like you may have a GPU problem. If you have your original disks can you run the AHT's (Apple Hardware Tests) Details on how to do this in the link below:

http://support.apple.com/kb/ht1509


This can eliminate hardware from the equation, and the second display option is also a good idea.

 

[littlefever]

It sounds like you may have a GPU problem. If you have your original disks can you run the AHT's (Apple Hardware Tests) Details on how to do this in the link below:

http://support.apple.com/kb/ht1509


This can eliminate hardware from the equation, and the second display option is also a good idea.

Thank you for your reply - these are good suggestions, but i've hit problems during this:

Startup holding C with the dvd in the drive: Souded like it were loading from the drive, but after a while (whilst still holding C, should i release the key at some point?), the screen grayed out and there were a messagebox telling me that i needed to restart my system.

Startup holding D as suggested didnt do anything.

So for now im left with the same two options as before - ill go find a cable for a secondary screen.

I will keep you posted : )

 

[Macman45]

Thank you for your reply - these are good suggestions, but i've hit problems during this:

Startup holding C with the dvd in the drive: Souded like it were loading from the drive, but after a while (whilst still holding C, should i release the key at some point?), the screen grayed out and there were a messagebox telling me that i needed to restart my system.

Startup holding D as suggested didnt do anything.

So for now im left with the same two options as before - ill go find a cable for a secondary screen.

I will keep you posted : )

You can release the key once the drive picks up, but it's sounding like a display problem. The monitor test will be the clincher...Keep us posted..

 

[littlefever]

So - a little update, and a cry for help...

Ive finally got a hold on the right cable for my secondary VGA - Just plugging it in the running iMac with no screen gives me another problem - i cant really, manually, tell the OS to just switch to the other screen - i can open the system pref./ screen through spotlight - but i cant really see where to click detect screens or whatever... So can anybody give me any advice whatsoever about controlling that process 100% blind... I have the feeling that the problem is solved soon - or at least the hope : )

Thanks

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Just saw something "new" - Does it tell you guys anything that the screen still switches of for powersave mode after 5 min, but from there i cant enter it again - but the OS is still running?

 

[Macman45]

^^^

Well, progress of sorts I guess...At least we know the problem is on the Mac display..Can't you open system preferences, then click on displays? Or don't you get enough time?

Will the system start in any other mode?:

http://support.apple.com/kb/HT1533?viewlocale=en_US&locale=en_US

The list gives you all the key combos for ALL start up options...One or more should by-pass any power options...Also, can you disable any energy settings you have from system prefs? If you can get in there, don't let the computer sleep, and turn off any screen savers you may have. This could be a resolution issue too, so see if you can alter the screen to a lower setting too.

 

[littlefever]

Oh - great ideas, but you are missing the point - i never get pass the apple logo and the spinning wheel - The wheel stops as the image freeze - my guess, on the switch to the OS backgrund image...

The iMac is in the office, so i will continue later : )