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My Imac boots up intermittently to a pixilated screen, or a white screen with vertical bars, sometimes goes as far a desktop, but that is pixilated as well and freezes. The AHT shows this code: Video controller error 4V DC 1140000003. External monitor shows the same pixilation as main monitor. My Question is where the video controller is located, and if I can fix this by simply replacing the logic board. Thanks for any tips.
Depending you your model it either uses an onboard GPU so you’ll need to replace the complete logic board or you have the higher end model which uses a MXM daughter board which might be all you need. Here’s the IFIXIT guide you’ll need to follow: iMac Intel 21.5" EMC 2308 Logic Board Replacement and you’ll need one of these: Intergraded Graphics: 3.06 GHz - 661-53053.33 GHZ - 661-5306 MXM Graphics board: 3.06 GHz - 661-53073.33 GHZ - 661-5420
