Upgrade MacBook Air 2014 2015 with normal M.2 SSD

MacBook Air models from 2014 and 2015 can be upgraded easily with standard M.2 SSDs. We show you how.

By replacing an older SSD with only 300 MB/s write speed you will also get better performance besides more capacity.

The MacBook Air 2014 and 2015 offers four PCIe Lanes for AHCI SSDs

The only problem to overcome is the fact that Apple’s SSD use a slightly different connector and are a bit shorter than M.2 SSDs. The solution for this situation is pretty simple though: we use a little adapter that gets placed between the new drive and the socket on the logicboard.

Apple uses PCIe SSD in this machines which use the AHCI protocol. The only existing SSD that you can buy new is the Kingston HyperX Predator. Regarding speed, two factors come into play: the SSD’s memory speed itself and the connection of it, made possible by PCIe lanes. The rule is: the more lanes and the newer the used standard, the faster it is. The 2014 and 2015 models use PCI version 2.0.

The MacBook Air 2014 can reach 1100 MB/s with a Kingston Predator.

Now it gets interesting: normally you only get a speed of around 700 MB/s in 2014 MacBook Airs, which is a good sign for the fact that exactly two PCIe lanes are used. The 2015 model can reach around 1200 MB/s, which is a sign for four lanes. Surprisingly, the older model also has four lanes on board, the speed limit is inside the SSDs! So we can make a 2014 model faster just by replacing the SSD.

But there is a catch: The first option is to use a 2015 original Apple SSD, which are pretty expensive – so this is not a good way to go. The better idea is to go with an adapter solution, but this is a bit tricky regarding the maximum speeds. We tested the configuration and reached the shown speeds of around 1100 MB/s. We realised, however, that the configuration in some MacBooks was not stable after coming back out of standby mode: the system just froze. Some other machines made use of the maximum speed without having any problems at all.

Furthermore, half of the time the SSD got only connected with two SSD lanes. This is exactly same same configuration as the original Apple SSD in the 2014 machine, so you don’t lose anything. If this happens in the 2015 machine though, you lose half of your maximum sequential speed. The good thing: when connected with only two lanes, the configuration was always stable.

So if you get a two lane connection, the speed is around 700 MB/s, if you get a stable four lane configuration you will get around 700 MB/s+ write and 1100 MB/s read speed. This was the Kingston HyperX Predator 240 GB. Bigger models should reach also around 1000 MB/s write speed. Compared to the original 2015 Apple SSD this is a bit slower, but much more price efficient.

The adapter solution is well worth it, just be prepared.

So we can list the following possible outcomes when upgrading a 2014 MacBook Air with standard M.2 SSD and adapter:

  • Apple SSDs from 2015 double the speed.
  • adapter configuration is stable when SSD gets connected with two lanes
  • adapter configuration is stable when SSD gets connected with four lanes
  • adapter configuration leads to freezes after standby, when SSD gets connected with four lanes

So the chances are almost 100% that you get a stable system. The chance to also double the speed (for the 2014 MacBook Air) or at least be on the same level (for the 2015 MacBook Air) is given, but not guaranteed. In configurations where we got a four lane connection but no stable operation, we dis- and reassembled adapter and SSD until only two lanes got recognised. After that, the system was perfectly stable.

For the MacBook Air 2015 these are the possible situations:

  • Apple SSDs from 2014 half the speed.
  • adapter configuration is stable when SSD gets connected with two lanes
  • adapter configuration is stable when SSD gets connected with four lanesd
  • adapter configuration leads to freezes after standby, when SSD gets connected with four lanes

So you get the same outcomes with the difference, that you already have a four lane SSD in the 2015 machine. So chances are 50:50 that you lose half of your sequential write and read speed. In everyday use, however, you shouldn’t care. If you need more capacity, this is the way to go. High sequential write and read speed are only important if you copy huge files everyday. More important are random 4k (small files) speeds, and these are on the same level with a two lane connection, too. You will not feel much of a difference.

So you can upgrade the MacBook Air’s last two generations with standard M.2 PCIe SSDs using an adapter. Doubling the speed for the 2014 model is a welcome bonus. Also positive is the situation that newer Apple SSDs are backward compatible. We had no problems in using a 2015 SSD in a 2014 MacBook.

It was impossible to find the factor being responsible for a stable four lane connection. We tried a few combinations, but it either worked or it didn’t. If you should decide for this upgrade path, please tell us your experiences to help others.

You can find all possible combinations for an upgrade on our upkeep pages:

Upkeep:     Replace MacBook Air SSD

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