27" 2012 imac - screen stuck @ 640x480 resolution

[macuserau104]

just unboxed my new 27" 2012 imac - after a 6 week wait for it to arrive.

first thing i did was run time machine to back it up on a new external 3TB HD.

it went to sleep during this and when i the screen opened up again the resolution is now stuck @ 640 x 480 i have tried all i can think of to resolve this with nil result.

i cant contact apple as it is the weekend here (australia) and have done a few searches on the net with no result

can any one help ?

 

[harlex]

have you done a full reset

 

[lali]

you have done the obvious steps right? settings-display play with auto or manual? I am away from my computer do not recall the menu names


if not you reset the smc http://support.apple.com/kb/ht3964?viewlocale=de_de&locale=de_de

 

[macuserau104]

more info

thanks for the help

have been using 10.7.5

mew mac shipped with 10.8.2 - tired restart, nil result

display pref only allows either:

- best fo display / scaled - it is stuck on best for built in display and if i choose scaled is back to best for built in display when i open it again

 

[drambuie]

What's weird is that 640 x 480 isn't an available option. The smallest scaled resolution is 800 x 600. It's like you have no video drivers installed, and it's fallen back to the VGA default of 640 x 480.

I notice you mention 10.7.5. I hope you didn't install that on your new iMac, as you would then have no drivers for the nVidia 6XX GPU.

 

[seanm9]

just unboxed my new 27" 2012 imac - after a 6 week wait for it to arrive.

first thing i did was run time machine to back it up on a new external 3TB HD.

it went to sleep during this and when i the screen opened up again the resolution is now stuck @ 640 x 480 i have tried all i can think of to resolve this with nil result.

i cant contact apple as it is the weekend here (australia) and have done a few searches on the net with no result

can any one help ?

I had a similar issue, try booting from the recovery partition... if the resolution is still the same it may be a hardware failure... also if you haven't reset the SMC and Zap the NVRAM...

 

[WilliamG]

I'd do a complete wipe of the system at this point, and reinstall the OS. Just start from scratch. Something software-wise got a little screwy, that's for sure.