tech support - mid 2011 21.5' iMac

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>I'd also like to note that several times there have been attempts to boot only to show vertical lines on the LCD (sometimes a mixed color, sometimes black & grey / grey & white) which last occurred June 16.

pic related

I don't know shit about macs. With that said, it could be your computer shutting itself down due to overheating, but it would normally do that mainly when being used for something intensive It could also be a failing power supply.

probably your gpu friend
use hirensboot cd to test your hardware more spec your gpu
idk how that shitty macs work but if you can take your gpu out take it and try using onboard for a while
if that isnt possible you're left with using software like hirensboot cd or another so see whats breaking down

>>341332
I run a third party app to monitor rpm/temps and they all showed normal readings
at times it would shut off in less than half an hour after being turned on with only browsing/youtube
>>341350
can a faulty gpu in a pc result in random shut downs? I'd like to note that about a week ago the computer was capable of staying on +1 hour while running Killing Floor on low settings until later shutting itself down after closing it and attempting to run a different game application.


https://www.macgurus.com/forums/showthread.php?26917-IMAC-2011-Will-not-power-on

after doing more research I've come across an iMac service manual for the specific model at hand (5th post down) on this forum up above.

It shows that LED #1 (indication that the AC cord is plugged in or mac is asleep) is lit.
LED #2 (indication that power supply is communicating with logic board) showing no light and is off.
LED #3 (video card >> motherboard) and LED #4 (LCD >> motherboard) are also showing no light and are off.

I'm not sure if LED #2 (power supply) is responsible for whether or not LED #3 (video card) & 4 (LCD) are also supposed to be on or not though

.

>>341221
Might be dried up thermal paste, bruh.

iMacs are a piece of shit to work on, so you can probably take it to a local 3rd party Mac repair shop if you can. Maybe the logic board needs to be replaced (since iMacs are AIOs, your CPU and GPU will be replaced since they're all on the logic board).

Also you might be able to run Tech Tool to see what's wrong. (try to find a newer version if you can).

https://www.macupdate.com/app/mac/19415/techtool-deluxe

>>341475
have considered this
Whether or not it is the source (although monitoring temps have shown CPU at mid ~40ºC) thermal paste will eventually be reapplied to both CPU and GPU
>3rd party Mac repair
Unfortunately this isn't an option so it'll have to be done here on the desk
>logic board
taken into consideration
>>341477
>https://www.macupdate.com/app/mac/19415/techtool-deluxe
thanks for showing me this, if i can get it to run long enough ill try it out