SSD pricing is slowly dropping to a reasonable price point that i argue everyone should at least have put their OS boot drive as an SSD and use traditional mechanical hard drives for large file and media storage.

For less than US$60, you can easily get a ADATA Premier SP550 240GB SATA-III SSD that has decent read and write speed that would improve performance on ANY desktop or laptop systems running on traditional mechanical hard drive by a magnitude of 2x-4x.  Laptop users would see an even larger jump in performance gains if their existing 2.5″ hard drive is only running at 5,400rpm.

SSDs vs Traditional hard drive speed

SSDs on SATAII and SATA-III vs Traditional hard drive speed. Graph credits to TomsHardware.

My current custom built Mac Pro consist of a Plextor M5S 256GB SATA-III SSD as my main system drive and a few Western Digital Caviar Black 1TB SATA-III 7200RPM drives for storage purposes. However the SATA-III interface have quickly become the bottleneck for newer and faster SSD due to the 600MB/s max interface speed.

PCIe vs SATA interface speed limit

PCIe 2.0/3.0 vs SATAII/III interface speed limit

This is where PCI-Express(PCIe) come in. PCI Express took over PCI/PCI-X/AGP as the main expansion bus for connecting additional peripherals. Like SATA, PCIe has evolved over time and the current motherboards using new chipsets has PCIe 3.0 slots for expansion. We have been using PCIe x8/x16 (the longest slot on your motherboard) for external graphics cards, like the EVGA GeForce GTX 750 SC i use on my system.

The large amount of bandwidth that PCI-Express offers is exactly what is needed to cater for newer and faster SSDs. Newer motherboards comes with a M.2 slot that connects directly to the PCIe bus. Unfortunately, i’m using a Gigabyte H87-D3H and it does not come with a M.2 slot for native support of M.2 SSDs. It does however have an extra PCIe x4 slot that i could use, after putting the EVGA GTX 750SC on the PCIe x16 slot.

I decided on the getting the Silverstone ECM20 M.2 to PCIe x4 adapter and a Samsung SM951 512GB (AHCI) M.2 80mm PCIe x4 SSD. After my research on Hackintosh forums, the AHCI (vs NVMe version) is required for better compatibility on custom built Macs. PC users can choose the slighter faster Samsung 950 Pro 512GB PCIe NVMe M.2 SSD.


Before unboxing the SM951 512GB SSD and the ECM20 Adapter. Note that the SM951 comes in a OEM packing instead of the Samsung retail box set.


SM951 installed on the M.2 key slot of the ECM20 adapter. I was surprised at how small the SM951 is.


Mac OSX detects the controller as Apple SSD Controller. Getting the AHCI version ensures full compatibility out of the box.

Some quick benchmarks comparing

  • Western Digital 1TB Caviar Black
  • Plextor M5S 256GB SATA-III SSD
  • Samsung SM951 512GB M2 PCIe SSD

Western Digital Caviar Black 1TB. 148.5MB/s write, 148MB/s read


Plextor M5S 256GB SATA-III. 371MB/s write, 474MB/s read.


Samsung SM951 512GB M.2 PCIe + SCM20 Adapter. 1367MB/s write, 1363MB/s read.

As my H87-D3H motherboard only supports PCIe 2.0 x4, my interface limited is about 1,500MB/s. If i upgrade to a PCIe 3.0 or a native M.2 PCIe 3.0 slot, i should be able to hit close to 2,000MB/s on the read speed, since on paper the specifications for the SM951 is “Sequential Read: 2150MB/s & Sequential Write: 1500 MB/s”.



As we can see from the graphs above:

  • 256GB Plextor SATA-III SSD vs 1TB Caviar Black = 2.85x performance gain.
  • 512GB SM951 PCIe SSD vs 1TB Caviar Black  = 9.22x performance gain
  • 512GB SM951 PCIe SSD vs 256GB Plextor SATA-III SSD = 3.2x performance gain

Still feel your computer is sluggish? Time to make that upgrade! 🙂