rMBP External Monitor Prevents Boot

hi all,

(possibly since 10.9.3 or 10.9.4) i've been having issue rmbp where, if turn on external monitor attached (via mini displayport, record), makes apple chime, starts loading, screen goes black , starts on message having restart due error. loop few times before giving , shutting off entirely.

"solution" far has been boot monitor unplugged, plug in after... except doesn't work either. 50% of time, in last week or so, doing causes external monitor not have work @ all. have reset computer couple of times every time turn on lately, becoming pain.

appreciated. i've tried resetting smc no avail, though i'm not positive did right. held shift, control, , option , power button released them simultaneously, magsafe light did not flicker or change states, told indicates worked. i'm not sure if happens, though.

 

boot hardware test. (restart, holding d key)
http://support.apple.com/kb/ht1509
(for hardware test, run both standard , extended tests)

if have mac released after mid-2013, may able run diagnostics, instead of hardware test.
http://support.apple.com/kb/ht5781

if test passes, try different video adapter/cable.

 

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