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Q: Macbook Pro -- Three beeps when both RAM slots used

I have a late 2011 Macbook Pro 17. I'm running Mavericks. I'm using two 8 GB modules of Corsair RAM, for a total of 16 GB. I've used these modules since I purchased the computer in 2011.

 

This weekend, while using a web browser my screen glitched out into green and purple blocks. I re-seated the RAM modules in the top and bottom slots, reset the NVRAM, and the computer worked for a little bit before glitching again while watching a video. The computer was incredibly hot at this point. After that, it could not be started, and instead I get a black screen with three beeps when I tried to start the computer.

 

My computer will work if I have either 8 GB module of RAM in either slot, as long as there is just one installed at a time. If I try to use both RAM modules, I get a black screen.

 

So: both sticks work with both slots, but if both slots are occupied at the same time, I get a black screen and three beeps on startup.

 

Is this a logic board problem? Could the RAM sticks be somehow touching each other and 'shorting out'? Or, since the problem seemed to involve the screen glitching, heat, and video-based applications, could the problem be related to the discrete graphics card somehow?

 

I apologize in advance if this question has been asked to death. I see lots of threads about 'Three beeps' but not much about this specific problem, of the use of both slots causing the problem.

 

Thanks!

MacBook Pro (17-inch Late 2011), OS X Mavericks (10.9.5)

Posted on Jun 15, 2015 2:24 PM

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