[bhouston]

I am confused generally. My old Dell xps 13 didn’t have thunderbolt but I could still use the exact same USB c to display port cable that I used on my Mac mini.

I am unsure if you need thunderbolt specifically to use USB c to display port cables. It seems you do not need thunderbolt but I am not an expert.

[ryukafalz]

> I am unsure if you need thunderbolt specifically to use USB c to display port cables. It seems you do not need thunderbolt but I am not an expert.

Correct, you do not need Thunderbolt for this. Most laptops with USB-C support something called DisplayPort Alt Mode, which is essentially DisplayPort over the type-C connector; I'd imagine that's what those cables are doing.

Now, if you have a Thunderbolt display specifically, like the ones Apple used to sell? Your type-C port would need to support Thunderbolt to use that.

[vetinari]

If you are using USB-C in alternate mode, it means that you forego everything else: with USB-C cable, you can basically use USB2, power delivery and (USB3 or alternate mode) at the same time.

Funny things happen when the alternate mode is Thunderbolt. It allows to tunnel DisplayPort and USB3 traffic, so when you are using TB alt mode, you still have usable DP and USB3, not USB-C natively, but packetized inside TB3 traffic.

For 2x20 GBit TB3 traffic, you need much better cable than what the average USB3/USB-C cable can handle (that's the reason why they are sold as TB cables); if it is anything above 0.5m, it is usually active one. And to make things even more interesting, there are USB-C cables than cannot handle even USB3/alt modes... so it is important to check the specs, not only price tag.

[microtonal]

If you are using USB-C in alternate mode, it means that you forego everything else: with USB-C cable, you can basically use USB2, power delivery and (USB3 or alternate mode) at the same time.

Incorrect. Perhaps with a low-end adapter, but with a higher end dock (and sufficiently modern hardware that supports DP1.3) you can drive 4k@60Hz [1], USB 3.2 Gen 2 10Gbit/s, USB 2, and PD at the same time over a single USB-C cable. For example, the Lenovo USB-C Dock Gen 2 that I use does this without any issues.

The configuration is that two superspeed lanes are used for USB 3.2. The other two superspeed lanes are used for DP-Alt, which have 8.1Gbit/s bandwidth per lane with HBR3 for a total of 16.2, which is perfectly fine for 4k@60Hz. You can even do higher resolutions with DSC (though I am not sure which, if any, docks support this).

[1] Or lower resolutions/refresh rates with HBR2.