In the hopes that those encountering the challenge of adding additional SSD storage to modern laptops may benefit from this learning experience...
Among the more popular standard-issue corporate laptops, the Dell Latitude E-Series product line has proven to contain a good mix of the qualities many look for: a reasonably small footprint, powerful CPU options, full HD graphics and room to expand both RAM and disk. Of note, I've used a Dell E7440 laptop for three years and liked it enough that once the corporate lease was up, I looked to buy a used one for personal consumption. As the E7440 is a bit long in the tooth now, I instead opted for the slightly newer, faster version -- the E7450. At the time of this publishing, these can be had on eBay for about $350 US.
What at first seemed to be a simple upgrade from the previous generation turned out to have one rather important difference: there is no supported secondary storage option on the Dell E7450.
As the image above demonstrates, the Dell E7440 on the left contains an expansion slot suitable for mSATA Solid State Drives whereas the connector on the right for the Dell E7450 instead includes a more generic (and more modern) mini PCIe slot. Cards for both, although somewhat similar at first glance, are not the same, do not have the same connectors and are incompatible. Here's what an mSata card looks like next to a 42mm mini PCIe card:
The Solution (for the impatient)
Not all mini PCIe cards are alike (more on this later). If you really don't feel like reading the rest of this article, one card has finally made it to market that does work in the Dell E7450 mini PCIe slot. That card is the Toshiba RC100 M.2 2242 240GB PCIe SSD, pictured directly below.
Note: The SSD may not automagically appear once installed in, say a Windows 10 environment. It may need to be partitioned and formatted first. And of course, as to whether it's officially supported by Dell is another question entirely.
More on Mini PCIe
Its arguable Dell was ahead of the game with respect to SSD connectivity for the E7450. The PCIe standard, and in particular the M.2 connector, is rapidly becoming more and more common, slowly but surely rendering mSATA obsolete. In addition to being available in many form factors, M.2 SSDs come with slightly different edge connectors or keys (which ultimately determine read/write speed) and can follow the SATA or NVMe (Non-Volatile Memory express) protocols. Let's examine these briefly now.
M.2 Form Factors
M.2 cards come in many different widths (12, 16, 22 and 30 mm) and lengths (16, 26, 30, 38, 42, 60, 80 and 110 mm). Some of these combinations occur far more regularly than others. The most common M.2 SSDs use 22 mm width cards with lengths of 30, 42, 60, 80 or 110 mm. A large majority of the M.2 SSDs currently available prefer the longer length form factors over the shorter ones, especially when considering larger capacity drives.
Often times the M.2 card will specify the dimensions as part of the model number. For example, the working module for the Dell E7450 (mentioned above) is the Toshiba RC100 M.2 2242 240GB PCIe SSD. The highlighted 2242 number indicates this card is 22 mm wide and 42 mm long. This form factor is not nearly as common as the longer types, and capacity is currently limited to no more than 256GB. No doubt as densities improve, this will change. The bottom line here is, the Dell E7450 PCIe slot is made for a 22 mm wide 42 mm long M.2 cards. The market for these types of SSDs are quite limited today.
M.2 Protocol for SSDs
M.2 SSDs are available as either supporting the SATA or the PCIe NVMe protocols. It is important to understand which of these protocols your laptop motherboard supports. Unfortunately, I was unaware of these differences, and in my ignorance initially purchased a Transcend 256GB SATA III MTS400 42 mm SSD. In the limited world of 42 mm M.2 SSDs, the SATA variety is by far and away the most prevalent and in fact until recently was the only option. Unfortunately the Dell E7450 does not support SATA on its PCIe interface. The picture that follows includes both PCIe M.2 SSDs. They both look the same. The Transcend device on the left won't work; the Toshiba device on the right does.
We won't get into much detail here, suffice it to say the M.2 edge connector can have different keying and notch configurations signifying among others, interfaces and transfer speeds. The cards in the image above are of the "B & M key" edge connector variety.
Here's the Dell Latitude E7450 with the Toshiba SSD installed.
And here's how in appears in the Windows 10 Device Manager