Building a cheap external SSD: USB 3 or Thunderbolt? 1 – Thunderbolt

As the cost of SSDs falls, I have been getting more tempted to buy a nice, big, fast external SSD. Something like a Transcend StoreJet, with Thunderbolt and USB 3 ports. The snag is that they are still alarmingly expensive. At the moment, Amazon UK – maybe hit by the falling £ – is offering 256 GB for £173, 512 GB for £280, and 1 TB for £464. That’s upwards of £0.46 per GB, but an equivalent 2 TB hard drive comes out at less than £0.09 per GB.

I was lucky enough to pick up a Crucial 750 GB SSD for only £110 in a recent Amazon sale – that’s just under £0.15 per GB, and a useful size too. The key question then was whether to get a USB 3 or Thunderbolt case for it. This short series of articles attempts to answer that question.

At first sight, this might not be a question at all. Thunderbolt SSD enclosures are very hard to find, and expensive. But I wasn’t prepared to simply plump for USB 3 without finding out the full facts. Having denigrated USB 3 so consistently and made the case for Thunderbolt, it was time to discover whether real-world performance reflected the specifications.


The Crucial MX300 may not be the best-performing SSD at the moment, but at that price I wasn’t going to haggle over brands. It’s a fairly standard package, a slim 2.5 inch SATA 6 Gb/s unit which should be blisteringly quick compared to any hard drive of similar size.


It comes with a spacer, in case you need one (only likely when fitting it internally), and a serial number for Acronis True Image HD backup, which doesn’t interest me.

Thunderbolt case

After a lot of searching, I concluded that the only Thunderbolt case intended for this situation is made by Delock, and costs around £95.


Designed for both SSD and HD storage, it ships with a printed instruction manual, Thunderbolt drivers for Windows, a European power supply, a free crosshead screwdriver for its bolts, some retaining bolts, and a neat little pouch for the drive. This already gives it a couple of disadvantages: it is not powered by Thunderbolt but requires its own supply, and (in the UK, at least) that supply needs another plug adaptor (seen here in white) costing a couple of pounds.

The other, more hidden, cost is that it does not come with a Thunderbolt cable, which will cost you at least £23. So the total cost of the Thunderbolt option has now risen to £120 plus the SSD itself.

You do get a high-quality alloy case for that, though, which you could equally use for any 2.5 inch hard drive.


Unscrew the pair of bolts at each end of the case and out pops the circuit board which makes it all work. Slide and plug the SSD onto that, then replace the board into the rails inside the case. Replace the ends, and it is ready to connect and power up. It is that simple.


The small hole at the right of the business end of the case is a standard status light.

The only minor gripe about assembly is the little screwdriver supplied: it’s slightly better than those which come free in Christmas crackers, but not really up to the job of opening the case up the first time. As usual, the bolts were overtightened in the factory, and I much preferred to use a screwdriver from my jeweller’s set, rather than risk burring the heads of the bolts.

For an SSD, I did not use the additional bolts supplied to secure it to the circuit board, but those are good, and entirely in keeping with this good-quality case.

I powered the drive up, connected it to my iMac, and initalised the SSD in Disk Utility. Everything checked out good, and it breezed through the performance and other tests as expected.

In the next article I will describe my USB 3 case, which cost a mere £15 – cheaper than the Thunderbolt cable alone.