Thunderbolt 3 and USB 3.1 2nd gen .... what a mess at DVinfo.net

Marcello Mazzilli · July 19th, 2017, 02:03 AM

Hi,
having bought a new iMac 2017 I am trying to understand better these new standards. I think I need some help here.

THUNDERBOLT 3 is 40 gbit and (differently from TB1 and TB2 that were using the rectangular connection identical to Mini Display Port) is using the USB-C connector.
USB 3.1 2nd generation is 10gbit but uses the same USB-C connector. USB 3.1 2nd generation (as ALL USBs) doesn't have daisychain.

On Amazon you can now find very few Tb3 devices (generally some expensive hubs or raids) while all the adapters/converters etc are actually USB 3.1 devices (allthough they say Tb3 compatibile). This means that maximum bandwidth is 10gbit (and sometimes you have to check as USB 3.1 gen 1 devices too might be using USB-C connectors). All these devices so DON'T HAVE a daisychain passthrough port. Some might have an USB-C port but is not a daisychain port... this will be only a Power Port to get extra power from outside (or to give extra power?). Many of these devices have also HDMI 4K output but, as far as I understand, this will be only 30Hz as 10gbit bandwidth will not allow more.

Also I found many Tb3 to Tb1/Tb2 adapters (quite expensive as they are real Thunderbolt, not USB-C) but I couldn't find anything the other way round, to connect my old Mac Mini's Tb1 to a new USB-C equipment (allthough they both have 10gbits). So I think this is not possible, allthough I am not sure.

I would like to buy hubs, raids, enclosures for external disks that are compatibile with both my new iMac 2017 (Tb3 with USB-C plug) and my old MacMini 2012 (Tb1). Obviously I expect the MacMini to go slower (max 10gbit) but I woul like it to work.

Ideally I would by Tb3 devices (real Tb3... not USB 3.1 gen2 with the USB-C connector as Tb3) and use a Tb1 to Tb3 (USB-C) adapter on my MacMini... but it seems impossible to find such adapter. Another solution will be to find devices that offer as a second input connector (together with Tb3) USB 3 (USB 3.0). My MacMini will be able to work allthough I will be limited to 5gbit (instead of 10gbit I would like).
Or I coulld buy Tb1 (one!) devices so I can be sure they will work on both machines (and buy a 80$ adapter for my NEW iMac 2017). This could work if I am buying a 2xSSD drive enclosure or even a 4xHDD raid as max speed should be within the 10gbit speed from Tb1, but would be quite a waste to get a Tb1 hub for external monitors for example as only new (and expensive) Tb3 hubs alloe 2x 4K (60hz).

Is it all correct what I wrote here?
Do Tb1 to USB-C (10gbit max!) converters exist somewhere ?

thanks,
Marcello

July 19th, 2017, 02:03 AM	#1
Marcello Mazzilli Major Player Join Date: Apr 2009 Location: ITALIA Posts: 416	Thunderbolt 3 and USB 3.1 2nd gen .... what a mess Hi, having bought a new iMac 2017 I am trying to understand better these new standards. I think I need some help here. THUNDERBOLT 3 is 40 gbit and (differently from TB1 and TB2 that were using the rectangular connection identical to Mini Display Port) is using the USB-C connector. USB 3.1 2nd generation is 10gbit but uses the same USB-C connector. USB 3.1 2nd generation (as ALL USBs) doesn't have daisychain. On Amazon you can now find very few Tb3 devices (generally some expensive hubs or raids) while all the adapters/converters etc are actually USB 3.1 devices (allthough they say Tb3 compatibile). This means that maximum bandwidth is 10gbit (and sometimes you have to check as USB 3.1 gen 1 devices too might be using USB-C connectors). All these devices so DON'T HAVE a daisychain passthrough port. Some might have an USB-C port but is not a daisychain port... this will be only a Power Port to get extra power from outside (or to give extra power?). Many of these devices have also HDMI 4K output but, as far as I understand, this will be only 30Hz as 10gbit bandwidth will not allow more. Also I found many Tb3 to Tb1/Tb2 adapters (quite expensive as they are real Thunderbolt, not USB-C) but I couldn't find anything the other way round, to connect my old Mac Mini's Tb1 to a new USB-C equipment (allthough they both have 10gbits). So I think this is not possible, allthough I am not sure. I would like to buy hubs, raids, enclosures for external disks that are compatibile with both my new iMac 2017 (Tb3 with USB-C plug) and my old MacMini 2012 (Tb1). Obviously I expect the MacMini to go slower (max 10gbit) but I woul like it to work. Ideally I would by Tb3 devices (real Tb3... not USB 3.1 gen2 with the USB-C connector as Tb3) and use a Tb1 to Tb3 (USB-C) adapter on my MacMini... but it seems impossible to find such adapter. Another solution will be to find devices that offer as a second input connector (together with Tb3) USB 3 (USB 3.0). My MacMini will be able to work allthough I will be limited to 5gbit (instead of 10gbit I would like). Or I coulld buy Tb1 (one!) devices so I can be sure they will work on both machines (and buy a 80$ adapter for my NEW iMac 2017). This could work if I am buying a 2xSSD drive enclosure or even a 4xHDD raid as max speed should be within the 10gbit speed from Tb1, but would be quite a waste to get a Tb1 hub for external monitors for example as only new (and expensive) Tb3 hubs alloe 2x 4K (60hz). Is it all correct what I wrote here? Do Tb1 to USB-C (10gbit max!) converters exist somewhere ? thanks, Marcello