Craig Col.

Q: Can’t boot iMac without dual monitors connected

Ok this is a weird situation.


I have 27inch Mid 2011 iMac, AMD Radeon HD 6970M 1024MB 32 GB RAM-


Currently I have it running with a 30inch Apple Cinema Display in dual monitor setup using an Apple Mini DisplayPort To Dual-Link DVI Adapter (with a USB connection as well)


The other day I tried to disconnect the external monitor so I can use just the iMac monitor and the computer immediately went into a kernel panic, rebooted (twice) and then tried to startup. As soon as it gets to the login screen it immediately reboots (twice) and repeats.


As soon as I hook up the external monitor it’s fine and reboots normally. The 30 in requires a USB connection to work and even if I just disconnect the USB cable it causes a kernel panic. Shutting down and then removing all cables results in same problem.

 

I’ve tried shutting down and unplugging everything, resetting PRAM, unplugged power cable to reset PMU, repaired permissions, starting in SAFE mode, etc.


Ideas?

Thanks!

iMac, OS X Yosemite (10.10.5), 3.4 GHz i7 / 24 GB Memory/ 1GB Vram

Posted on Aug 28, 2015 9:35 AM

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