I have a MacBook 7,1 which i recently installed a PNY 250 SSD and added some RAM. The laptop was running awesome with OSX 10.6.8, lightning fast.

Then I installed Yosemite. There was a bit of hang during the install, but Yosemite came up no issue when I rebooted. Here is the problem:

Every other time I boot the MacBook it hangs at a grey screen with the prohibitory sign. Verbose reveals a "still waiting for root device" error. Now if I reboot from that hang, it boots fine, but then will hang again the next time. It keeps alternating like this. Any ideas??

I am not running any third party trim software, so that's not the issue.

  • if it were an HD, I'd say it's not spinning up quickly enough… so I'm stumped
    – Tetsujin
    Nov 28, 2014 at 16:28
  • All I can think off is: Apple has tighten the non apple hardware check in Yosemite (including the SSD). It is called the kext signing. cindori.org/trim-enabler-and-yosemite I know you have not enabled trim but ? If you can provide us with Console log of the boot process.
    – Ruskes
    Nov 28, 2014 at 17:31

1 Answer 1


try resetting your PRAM and SMC, this may resolve your issue,



otherwise it could be bad RAM... take your Macbook in to apple and have them test the RAM.

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