Accelsior S Review: Give Your Mac Pro a Performance Boost

Accelsior S
The Accelsior S.

Other World Computing

The Accelsior S is one of the least expensive SATA III cards available for the Mac Pro. It supports a single 2.5-inch drive mounted to the card and connected by a standard SATA III connection. While other SATA III cards include multiple SATA connections, the Accelsior S single SATA III port is available at a significantly lower cost. In fact, it's low enough that if we should ever need a second SSD, we can easily purchase a second card, and still be near, or even lower than, the cost of some competitors' dual-port cards.

What We Like

  • PCIe 2.0 x2 provides enough bandwidth for SATA III SSD.

  • Half-height, half-length card for easy installation.

  • ASMedia 1062 controller doesn't require any drivers for use with OS X.

  • Bootable.

What We Don't Like

  • OS X considers a drive connected to Accelsior S to be external.

  • Can't be used for Boot Camp.

Installing the OWC Accelsior S Card

The Accelsior S card is delivered with just an install guide and a set of four screws for mounting a 2.5-inch drive (not included). The most difficult part of the installation is picking an SSD brand and size to mount to the card. I selected a 512 GB Samsung 850 EVO that happened to be on sale.

Installation is a two-step process that begins with mounting the 2.5-inch drive to the Accelsior S by sliding the SSD (or any 2.5-inch drive) into the SATA connector on the card. Then, while flipping the card over, use the four included screws to secure the drive to the card.

With the drive secure, the second step is to install the Accelsior S card in your Mac Pro.

Start by shutting down your Mac Pro and then removing the side access plate. Remove the PCIe card slot bracket, and install the card into an available PCIe slot. For best performance, you should choose a PCIe slot that supports four lanes of traffic. In the case of the 2010 Mac Pro, all available PCIe slots will support at least four lanes. Earlier Mac Pro models had specific lane assignments by PCIe slot, so be sure to check your Mac Pro manual.

Reconnect the PCIe card slot bracket, and close up the Mac Pro. That’s all that's needed for installation.

Using the Accelsior S

We're using the Accelsior S and the SSD that's attached to it as the startup drive. Once formatted, we cloned the existing startup to the new SSD using Carbon Copy Cloner, though we could just as easily have used SuperDuper, or even Disk Utility, to clone the startup information.

We also took the time to move the user data to one of the available internal hard drives. This ensures that the SSD will always have enough free space to ensure optimal performance.

Accelsior S Performance

We used two drive to benchmark utilities: Disk Speed Test from Blackmagic Design, and QuickBench 4 from Intech Software. The results from both benchmarking apps showed that the Accelsior S was able to deliver very close to what Samsung says is the top-end speed for sequential writes and sequential reads.

Benchmark Utility Sequential Writes Sequential Reads
Disk Speed Test 508.1 MB/s 521.0 MB/s
QuickBench 510.3 MB/s 533.1 MB/s
Samsung Spec 520 MB/s 540 MB/s
Accelsior S Performance

TRIM and Boot Camp

As mentioned in the cons, the drive connected to the Accelsior S is considered to be an external drive, but that doesn't impact making use of TRIM support, if you wish to. While it's true that TRIM won't work for external USB-based SSDs, it works fine with the Accelsior.

While TRIM will work, Boot Camp won’t. The problem here is that the Boot Camp utility that partitions and helps install a Windows environment will fail on the installation process since it sees the target device as an external drive. When it first created Boot Camp, Apple decided not to support installation on external drives. Although Windows itself will work from an external drive, Boot Camp won't allow the install process to proceed.

Final Thoughts

The Accelsior S delivers on its promise of top-notch performance at a very reasonable price. It doesn't get in the way of delivering what the top end of today's SATA III-based SSDs can deliver, and in the end, that's the best recommendation of all.