In this second instalment of the two-part blog series, we have a look at PCIe (PCI Express) SSDs, what they are, what products are currently available, and the performance benefits they can bring to your Apple Mac computer.
In part 1 of this 2-part series I discussed the relevance of PCIe SSD's to Windows / Linux systems. In this, the second instalment, I'll look at the benefits of this relatively new technology in relation to Apple Mac computers, with specific attention on the 2006-2012 model Mac Pro tower systems.
SSDs: from SATA to PCIe
In part 1 I discussed the evolution of Solid State Drives from SATA to PCIe, so for a quick primer, read that post.
What type of SSDs are used in Macs?
In most post 2006 Macs, traditional 2.5-inch SATA based SSD's such as the 2.5inches SSD's are compatible and are a good upgrade option for an existing mechanical hard drive. Even the original MacBook Pro 1,1 with it's old 1.5GB/s SATA interface is considerably snappier running an SSD, even though the maximum sequential speeds are limited to about 200Mb/s read and 180Mb/s or so write.
The exceptions to the 2.5" SATA SSD rule are the newer Retina-screened MacBook Pro and all models of the MacBook Air. These machines ship from Apple with custom SATA-based SSDs, and although Apple never intended for the SSD to be upgraded, it is quite easy to do so with a specifically manufactured upgrade SSD like the Transcend Jetdrive.
Moving up to PCIe SSDs
Fast forward to 2013, and this is when Apple first started to deploy PCIe SSDs in the Late 2013 (Retina Display) Apple MacBook Pro. The M.2-based PCIe SSD used in these machines is a customised version of the Samsung XP941, only built with a non-standard connector. These new SSD's allowed Mac owners to surpass the old ~550Mb/s sequential datal transfer speed bottleneck, with internet forum users reporting speeds of 730/670Mb/s read/write respectively on the 256GB specc'd MacBook Pro Retina models.
Not long after Apple released the new cylindrical Mac Pro which also utilised the same PCIe SSD for storage. To date, no other third party SSD manufacturers have managed to replicate this drive to provide an upgrade path.
PCIe SSDs in the 2006-2012 Mac Pro
In mid 2013, Samsung released the XP941 - a M.2 format PCIe 2.0 x4 (4-lane) SSD which is still the only one of it's type in mass production. At the time there really weren't any motherboards with the required M.2 socket to take advantage of this drive. However it wasn't long before Taiwanese manufacturers began producing a suitable adapter card to allow the XP941 to be installed in a standard PCIe slot.
Later in 2013, internet forum users discovered that the XP941 and adapter card was a compatible (and bootable) storage solution in all models of the Apple Mac Pro (all those before the new cylindrical model was released). This provided a massive performance boost, with Mac-performance website barefeats.com recording sequential transfer speeds of 1168/979Mb/s read/write respectively on a single 512MB drive.
Current PCIe internal SSD product upgrade options for Macs
As mentioned earlier in the article, the latest model Retina MacBook Pro and Mac Pro utilise a PCIe-based SSD for which there is currently no third party upgrade available. However, if you own a 2006-2012 model Mac Pro, you have one option:
Samsung XP941
The Samsung XP941 is a stand-alone M.2 format SSD, and although a diminutive 80mm long and 22mm wide, is currently the fastest performing PCIe SSD available in its respective 128/256/512GB capacities.
To install the XP941 in the Mac Pro, you need to couple it with an adapter card. You can also install multiple SSDs and adapter cards and configure them with software RAID for higher performance.
Full product and compatibility details of the Samsung XP941 are here.
Our personal thank you to Rod who wrote this excellent tutorial