Can I use USB-C with Thunderbolt v1 on my 2011 iMac?

vkd1008 wrote:

I have a 2011 27" iMac which has 2x Thunderbolt v1 ports. These ports are miniDP type but you can't use a standard DP cable, it has to be a special Thunderbolt one.

That's not accurate. You can use a standard DisplayPort cable when using that port to connect a DisplayPort monitor to the iMac. It's only when you want to make a Thunderbolt connection that you must use one of the special, higher-grade Thunderbolt cables

My question is, for my use case, can I use a standard USB-C male to USB-C male cable, with a USB-C to miniDP adapter? Will that work?

What is your use case?

If you are hoping to use this iMac as a Target Display, a USB-C to Mini DisplayPort adapter will not work. Once iMacs got Thunderbolt ports, Target Display Mode required a Thunderbolt signal. You'd need to spend $80+ on specialized connection hardware to make a Thunderbolt data connection between a Thunderbolt 3/4/5 port on a current Mac, and the Thunderbolt 1 port on that old Mac.

On top of that, Apple later added restrictions to Target Display Mode. Now the source has to be an old Mac; one with a hardware model year of 2019 or earlier, running Catalina or earlier.

Can I then put a USB-C female to female USB type A (but USB 3.1) adapter (yes it is confusing, I know) and plug an external HDD to it to get better transfer rates than the standard USB 1.1 ports on this iMac?

No. Running some sort of jury-rigged connection from USB-C on a newer Mac, into one of the Thunderbolt 1 ports on an old Mac, with a USB-C to Mini DisplayPort adapter in the mix, will not work. The newer Mac will be sending a DisplayPort signal to the old Mac and will not be sending a USB or Thunderbolt one. The old iMac does not accept plain DisplayPort input, so at best, nothing would happen.

It is theoretically possible to add USB ports using Thunderbolt 1, but definitely not in the way that you proposed!

As for there being no new products on the market to do this directly, once Intel moved Thunderbolt to the USB-C connector, vendors started discontinuing their Thunderbolt 1. & 2 docks. They did not see a big enough market in continuing to make the old-style docks to make it worth their while.

You can use an Apple Thunderbolt 3-to-2 adapter to connect a Thunderbolt 3 dock to an old Mac with a Thunderbolt 1 or 2 port, and OWC sells such a bundle. Note that this will not make things run at Thunderbolt 3 speeds; the old Mac’s slow Thunderbolt port will be a bottleneck. Also, this will not work with Thunderbolt 4 & 5 docks and peripherals; those are not backwards compatible with Thunderbolt 1 & 2 hosts even with the use of an adapter.

vkd1008 wrote:

I'm not interested in sending video signals, its data that I want to use the Thunderbolt port for. I want to connect an external HDD to it.

You can not connect a USB external HDD to those ports.

You will need to connect the external HDD to one of the iMac's USB 2.0 ports.

If it is USB-C external HDD, then you will need a USB-A to USB-C adapter.

Re: “You and others were previously hung up on this whole video conundrum, whereas I am not in the slightest bit interested in sending video, I just want to connect an external HDD and read and write data to it.”

Most people who come in here looking to connect new Macs to old iMacs want to use the latter as monitors. When you mentioned using a USB-C to Mini DisplayPort cable, that, at first, gave me the impression that your use case was yet another Target Display Mode one.

Your options for connecting an external hard disk are to use USB 2, to use FireWire 800 (OWC still sells desktop FireWire 800 + USB 3 drives and enclosures), or to pay big bucks to connect a Thunderbolt 3 dock using a $50 adapter, and still have USB speeds limited to less than 10 GOPs.

You cannot connect a USB drive to the Thunderbolt port using a USB-C to Mini DisplayPort adapter that can only output video signals, not USB or Thunderbolt ones.

vkd1008 wrote:

But you were just opining that the Thunderbolt v1 ports on the 2011 iMac are only MiniDP. The format of the port is MiniDP, yes, but the connection is Thunderbolt which carries video and data. You and others were previously hung up on this whole video conundrum, whereas I am not in the slightest bit interested in sending video, I just want to connect an external HDD and read and write data to it.

It seems quite ludicrous that successive Thunderbolt generations are all backwards compatible but it seems the original v1 Thunderbolt is absolutely condemned and according to you cannot even be converted to USB, whereas there are/were Thunderbolt 1 docks available (at sky high prices) that provide myriad output formats. Likewise for Thunderbolt 3 & 4, only much more readily so. To state that you cannot connect USB to Thunderbolt 1 does not sound very educated.

I know what you are trying to do because I explored these options on my 2015 iMac, which has USB 3 and Thunderbolt 2 ports. I wanted the faster 20 Gbps Thunderbolt 2 speeds versus 5 Gbps offered on its USB ports. I obtained a Thunderbolt 2=>3 adaptor and found that this adaptor cannot carry power. Hence I obtained an OWC dock that had its own power. But this setup still did not work, none of the drives connected to it via its USB-C ports worked with this setup. In the end I am just using the iMac's USB 3 ports which at 5 Gbps are fine.

Your 2011 iMac is quite obsolete and as you are finding, because there is virtually no demand for such old Thunderbolt 1 products and converters, whatever you find is very costly. Its Firewire and USB 2 ports will be very slow. With Thunderbolt 3 and 4 products in the household and fast internal and external SSDs, I find USB 2 speeds intolerable; hence with my museum piece (2010 MacBook Air), I keep it running sort of for fun but never connect anything to its USB 2 ports (which were state of the art when we purchased that laptop).

I think you will find your Thunderbolt 1 ports are not really usable because there are almost no products available on the market that work well with it, or if you manage to find one on eBay, it might have issues or will be very expensive. I would get a more modern Mac, if price is an issue OWC and Apple sell very reasonably priced refurbished devices. No need to throw the 2011 iMac away, it can be your museum piece, but in today's world, it is impractical for most uses.

Yes, you can use a Thunderbolt dongle to get to newer Thunderbolt, but a chain dongles and a dock may well be worth more than this iMac 27” Mid 2011 is worth.

You don’t get USB out of a Thunderbolt 1 port, though.

You can get to Thunderbolt storage, or probably also a Thunderbolt dock that has faster USB available.

Wrong answer follows (for the Mid and Late 2011 iMac 21.5” models), as I previously missed the 27” part.

That’s a mini DisplayPort connection, not Thunderbolt.

It only does DisplayPort, not Thunderbolt.

Available storage connections are USB 2.0, FireWire 800, Ethernet, and 802.11n Wi-Fi.

This visual guide might help clear up the confusion:

Identify the ports on your Mac - Apple Support

"Thunderbolt and Thunderbolt 2 are not the same as Mini DisplayPort. They have the same shape, but use different symbols on the cable and port. However, this port does support Mini DisplayPort for video output, so you can use a Mini DisplayPort cable to connect a Mini DisplayPort display."

and conversely,

"Mini DisplayPort is not the same as Thunderbolt or Thunderbolt 2. They have the same shape, but use different symbols on the cable and port."

vkd1008 wrote:

I have a 2011 27" iMac which has 2x Thunderbolt v1 ports. These ports are miniDP type but you can't use a standard DP cable, it has to be a special Thunderbolt one.

Those ports are only Mini DisplayPort.

Thunderbolt v4, the latest, and Thunderbolt v3 have USB-C format. Cables are interchangeable between Thunderbolt 3/4 and USB-C.

That is true.

My question is, for my use case, can I use a standard USB-C male to USB-C male cable, with a USB-C to miniDP adapter? Will that work?

No Mini DisplayPort does not convert to USB.

Can I then put a USB-C female to female USB type A (but USB 3.1) adapter (yes it is confusing, I know) and plug an external HDD to it to get better transfer rates than the standard USB 1.1 ports on this iMac?

Yes and FWIW, the 2011 27" iMac has USB 2.0 ports, which are way faster than USB 1.1 ports.

iMac (27-inch, Mid 2011) - Technical Specifications - Apple Support

vkd1008 wrote:

Thunderbolt v4, the latest, and Thunderbolt v3 have USB-C format. Cables are interchangeable between Thunderbolt 3/4 and USB-C.

Thunderbolt 3, 4, and 5 all live on the USB-C connector … and any certified Thunderbolt 3, 4, or 5 cable is likely to be suitable for non-Thunderbolt uses.

But there are many USB-C cables that are not suitable for carrying Thunderbolt. There are some "charging" cables that don't carry data at all; others that are only suitable for carrying USB data at USB 1 and 2 speeds; and so on.

As with Thunderbolt 1 and 2, if you're making a Thunderbolt connection, you need to be using a Thunderbolt cable that was engineered to reliably handle the high data rates associated with Thunderbolt.