MacBook – Upgrading MacBook Pro mid-2009 RAM

macbook promemoryupgrade

I'm trying to upgrade my MacBook's RAM to 8GB (2×4 GB), but somehow when I install the new cards I got the 3 beeps + 5 seconds pause. The 4GB cards were already working in another early 2011 MacBook.

The point being that, if I install the memory in a mid-2009 in a 2GB+4GB configuration, the Mac runs well. I have tried to switch cards and slots and it works, too.

Does anyone know what's happening?

Best Answer

3 beeps + 5s pause means your memory failed training. There are a LOT of reasons this happens. Let’s consider the most common.

First, let’s make sure your system supports 8 GB. According to Apple, the mid-2009 MacBook Pro does support up to 8 GB:

4GB (two 2GB SO-DIMMs) of 1066MHz DDR3 memory; two SO-DIMM slots support up to 8GB

Now let’s consider a couple of possibilities:

  1. It may be that one of your 4 GB SO-DIMMs is of marginal quality and is failing during one of the training steps. Let’s rule that out. When you ran your experiment, did you try both of the DIMMs alongside the 2 GB DIMM? And then did you try each of those DIMMs in the other slot alongside the 2 GB? In other words, you should have performed this experiment with FOUR different memory configurations.
  2. Although I can’t think of a good reason why it would only happen for the 4+4 case, your firmware may not be recognizing a new DIMM has been installed and is trying to use a stale memory training table with the new card. You can force full memory retraining by resetting your PRAM (OptionCommandPR during boot).
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