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Mac Pro 5.1 won't reset pram

Mac Pro mid 2010, 27in display starts with vertical strips, can't boot to diagnostics, can't reset pram, can't boot to recover or safe mode. When start button is held at start up eventually a flat long tone given then the chime tone but no change to stripped display.

Seems like USB keyboard not functioning in addition to display being sent bad video

Mac Pro, macOS High Sierra (10.13.3), 8 processor, factory 4 2gbyte Simms

Posted on Mar 17, 2018 9:35 AM

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Mar 17, 2018 7:52 PM in response to david777x

Holding the power button is used to enter a special mode that allows Apple free-standing firmware updates to be applied. The tone is the signal to YOU, "OK, I am going to run your firmware update now." However, since you did not queue a firmware update to be applied, the tone sounds, then nothing happens.


There ARE failures that are signaled with tones on other Macs, but on the Mac Pro the power light alone provides the signal. Three tones indicates "Not enough working RAM to start up" and there is another pattern that indicates "firmware checksum error".

Mac Pro 5.1 won't reset pram

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