Tag Archives: x16

Twice the Speed? USB C-ing Things!

During this past weekend, I heard from my client from May, on whose Dell PC I had performed a clean Windows 10 installation. Since I last reported, we’ve done a RAM upgrade (from 12 Gigabytes to 16); and we’ve added a spiffy new graphics card. These upgrades have extended the usefulness of the now nearly seven-year-old PC. And it continued to run swimmingly, until a recent video editing assignment took things to a new level.

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A new graphics card can make a huge difference for a PC. Source: MSI.com

The client was handed two portable hard drives, each holding two Terabytes (TB) of footage. This was too much to transfer to the PC’s internal hard drive, so she had to run directly off the externals. That’s not an entirely unreasonable task, as we had installed a USB 3.0 card some time earlier, and that allowed her to input data at five Gigabits per second (5 Gbit/s). But she was still experiencing a frustrating lag when trying to play video directly from the drives. When she called, I asked her to provide me with the model numbers of the drives, so I could get a better sense of what we were working with.

“MU-PT2T0B,” she texted me. This is the model number for Samsung’s T3 Portable Solid State Drive (SSD).

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Samsung’s T3 Portable SSD. Note the shape of the port on the left. Source: Samsung.com

Checking out its specs on Samsung.com, I saw one line that intrigued me:

“USB 3.1 Interface”

I thought to myself, “Three… point… one?

No, just 3.1!

I remembered the blog post I did last November about the advent of Thunderbolt 3, and how it shared the rounded, “USB-C” connector shape with the nascent USB 3.1 format.

Okay, there it was, bottom of the chart:

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This is where things get a little messy. On their website for the  portable SSD, Samsung doesn’t get into which USB 3.1 standard the drive uses: 3.1 Gen 1 (formerly 3.0) with a top speed of 5 Gbit/s; or Gen 2, which, as you can see in the chart above, is twice that speed. All they say as far as speed is, “450MB/s Transfer Speed.” If that seems slow, note the capital “B.” That indicates Megabytes, as opposed to Megabits. It’s a subtle difference, but a Megabyte is equal to 8 Megabits. That means 450MB/s (Megabytes per second, mind) is 3,600 Mbit/s (Megabits per second). Applying the metric system, this becomes 3.6 Gigabits per second (Gbit/s). It’s still within the threshold of USB 3.0’s 5Gbit/s speed, but I wanted to try something nonetheless.

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This chart shows how USB 3.0 became 3.1 Gen 1. Honestly, this whole mess could have been avoided if “Gen 2” had just been called, “USB 4.0.” Source: Kingston.com

Adding USB 3.0 ports had been a simple, effective upgrade. Would it be just as helpful to add 3.1 ports? I went to my local Fry’s Electronics to look into it. If the upgrade was too expensive (or unavailable), then we’d just carry on at 3.0 (or 3.1 Gen 1, whatever you want to call it) speeds.

As it turned out, Fry’s had a wide variety of affordable 3.1 cards. But a closer look indicated that many of them were indeed “Gen 1,” and thus offered no speed boost over the “3.0” card we had installed a while back. I had to keep my eyes peeled for that essential piece of fine print.

I did find a few that offered 10 Gbit/s speeds, but the connectors gave me pause. You see, most 3.1 cards either use just the old, rectangular “USB-A” ports; or they go 50/50, with one rectangular port, and one rounded “USB-C” port. Both potentially work at the full Gen 2 speed, but I was thinking about my client’s Samsung drives. I wanted to go directly from each of their native USB-C ports directly into the computer’s, without using an adapter cable, or a hub (and more on that in a moment). We had two drives, so I wanted two USB-C ports (at that full Gen 2 speed, remember).

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A typical USB card with both shapes of the USB 3.1 interface. Source: Frys.com

Luckily, after a little digging, I found the only card in the store that met my needs: The Xtrempro 11107 PCI-E 2Ports USB3.1 Type-C Card (just rolls off the tongue, don’t it?). It met both my needs: 10 Gbit/s transfer speeds, and two USB-C ports. All that, at less than $30.

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And this is the FRONT of the box! But at least it doesn’t leave anything to the imagination!

I did, though, have to buy some cables: an internal power cable to run from the PC’s power supply to the USB card; and of course, two USB-C cables to connect those Samsung drives to this new card. When shopping for the USB-C cables, I was just as diligent about reading their specs as I had been about the card’s. I didn’t want the cables to choke on the full data rate promised by Gen 2, after all! Several USB-C cables I found were indeed only rated at 5 Gbit/s, so I’m glad I didn’t fall for the old “they all look the same” trap. I eventually grabbed a pair of PPA Int’l cables, after reading on their package, “Up to 10 Gb/s.”

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PPA’s USB-C cable. Source: ppa-usa.com

So I brought everything to my client, and we opened up her PC. The next consideration was where I was going to put this card. You see, a motherboard’s expansion slots can be just as prone to the “they all look the same” trap as the cables. And that can make a huge difference. Her motherboard contained six slots, all based on the Peripheral Component Interconnect (PCI) standard. One slot (labeled 25 in the diagram below) uses the original PCI format, capable of speeds between 133 and 533 MB/s (note that capital “B,” as in Megabytes). The other five use the newer PCI Express format, capable of anywhere between 250 MB/s and 63 GB/s. And that’s a pretty wide range, so let’s narrow it down a bit.

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Dell’s schematic for the motherboard. Note the PCI slots toward the lower-left. Source: Dell.com

Slots 26, 29, and 30 are what’s known as PCI Express x1. This is a “single-lane” link, which means the following, according to howstuffworks.com:

Each lane of a PCI Express connection contains two pairs of wires — one to send and one to receive. Packets of data move across the lane at a rate of one bit per cycle. A x1 connection, the smallest PCIe connection, has one lane made up of four wires. It carries one bit per cycle in each direction.

Slot 28, an x16, was already in use by the snazzy new graphics card we got—and rightly so, as that’s the fastest PCI connection on the motherboard, and where better to put the indispensable graphics processor!

This left #31, which I’ll call, “Goldilocks.” It’s neither too slow, like its x1 siblings; nor too fast, like the x16 slot. This slot runs at x8, which—I checked—the new USB-C card supports.

So I installed the card into that x8 slot; and after running a power line to it from the internal power supply, we were good to go. We connected the Samsung drives directly to the card, and suddenly video that couldn’t even open was now coming up, buttery-smooth. We were no longer at the mercy of a 3.0 card in an x1 slot. We were now coasting at 3.1, Gen 2, via x8. And apparently, those numbers make all the difference.

EPILOGUE

I thought about the prospect of adding a third USB-C component in the future, like another Samsung drive, via a hub. To my surprise, as of this writing, nobody has manufactured a hub that supports the USB-C shape and the Gen 2 speed of 10 Gbit/s. I have reached out to the USB Implementers Forum at usb.org, to see if they know of anyone who has built such a device. I’ll post if and when I hear back from them. Until then, it appears if you want to connect more than two USB 3.1 (Gen 2) devices to a PC, you’ll need to use adapter cables. So make sure they don’t slow you down.

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A typical “USB-C Hub,” from Macally. Except it only connects (right) via USB-C, and the USB-C port on the left is only for passing through a charge into a laptop. The USB ports included are both the older USB-A shape, as well as the slower 3.0 speed! Hopefully, newer, better hubs are on the way.

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