Does the Clevo P750TM1 have one or two Thunderbolt ports?

The Sager 9156 is based on the Clevo P750TM1 chassis. According to Sager's specifications, it has a single Thunderbolt 3 port on the left, and two USB 3.1 Type C ports. Obviously, one of those is also the Thunderbolt port. This is the same as the Eurocom Sky X4C, which I have. Indeed, only one port has the label.

However, there are two curiosities. First, I can connect an external Thunderbolt enclosure to either USB 3.1 port. When I do so with an NVMe SSD in the enclosure, both ports give approximately the same read speed in CrystalDiskMark: 2600 MB/s, or over 20 Gbps. This is well over the 10 Gbps limit of USB 3.1 Type C by itself, but well within the 40 Gbps limit of Thunderbolt 3. Second, the Thunderbolt utility shows two ports, and will detect a Thunderbolt device in either USB 3.1 type C port.

So does the P750TM-1 have one Thunderbolt-3-capable USB port, or two? And a bonus question, which I have not been able to test: If it has two, do they work simultaneously at maximum throughput? Or are they sharing lanes or controllers somehow? To test this, ideally you'd need two fast Thunderbolt drives.

 

Officially and as far as I was aware it was one port as per the manual.

 

The Thunderbolt 3 controller (Titan Ridge most likely) has 2 ports. However, it can only be a Thunderbolt3 certified port if DisplayPort is also mux'd in on said port. Without the DisplayPort component, it simply acts as a USB 3.1 Gen2 + PCIE port.

As you've noticed, both ports are indeed fed by the Titan Ridge chipset, but only one of them will have DP mux'd in.

For historical reference, the old P600 series used the Alpine Ridge Thunderbolt3 controller, but since Clevo didn't mux in DisplayPort, it just acted like a dumb (albeit expensive) USB 3.1 controller.

 

But both ports still individually operate at faster than USB 3.1 Gen 2 speeds. So are they sharing a 40 Gbps connection?

 

The "non-TB3" port is not operating in USB mode. It can still run as a PCIE x4 port, hence why you're getting ~20gbps.

You should be able to see this using something like HWInfo. The NVME drive should appear on the PCIE bus rather than USB.

 

So the Thunderbolt port can get up to 40 Gbps and the other port can get up to 4 PCIe lanes worth? Wouldn't that be up to 30 at least? Judging from my internal NVMe drives.

 

You could still be running into other bottlenecks. Keep in mind you're still going PCIEx4 into the TB3 controller, which only has PCIEx4 to the chipset, which then only has DMI 2.0 (~PCIEx4) to the CPU. Lots of things will get in the way there.

 

Wait a second. If the controller only has PCIe x4 to the chipset, wouldn't the Thunderbolt port be only 32 Gbps (4*1 GB/s) at most? Even though the Thunderbolt 3 standard is 40 Gbps? And with both ports on the same controller there's no way it's getting more than 40 Gbps even if you used both at once, right?

 

Thunderbolt is only 32Gb for non video data after overheads.