Screen defects, extremely slow but not 100% dead
A few days ago our iMac got some wierd screen artefacts out of nowhere. The varied a bit but mostly horizontal lines on the screen. The night this happened the computer was extremely warm on the back top left corner (if it is of any help).
We could continue to use the computer with the display issues for a few days but it did not improve so it was more or less useless. Finally it did not complete the boot sequence unless we started it in "safe" mode but at least we could login still.
We decided to try a clean install and now things started to become even worse. After trying to reinstall Lion the screen is filled with graphical defects and we never get past the grey boot screen, no login window etc not even in safe mode.
When trying to boot from a DVD with Snow Leopard, it actually appears as it is indeed reading from the disk and the screen is actually consistently blue with no graphic defects unless for the pointer, which is a square of graphic bugs floating around. However it never gets anywhere when trying to boot from the disk, it just gets stuck.
We can still get to the boot menu screen with the options to re-install etc but it is filled with graphic defects and so incredibly slow. I can for instance see in the start disk menu that it identifies the Snow Leopard disk in the drive and I can set it to boot from this disk and restart. However performing this steps of selecting the disk, pressing restart and confirming takes about 5 minutes since the system is so incredibly slow even in the boot menu application.
I am quite curious, it looks very bad but I am also surprised that things are working a little bit. I was expecting things to be either on or off, here we are somewhere in between where the iMac obviously is not completely gone but it is very close.
I will have to take it to service I guess but since it is 4 years old it might just not be worth it so if anyone has any ideas on what might be wrong it is highly appreciated. If we are fighting with a corrupt DRAM module, jippii but if everything points to the logic board then I guess we are screwed :-(
All suggestions welcome