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Discussion in 'iMac' started by Jong875, Apr 26, 2019.
It's hard to find this info, but are the 4 USB ports 3.1 Gen 1 or Gen 2?
Four USB 3 ports (compatible with USB 2)
Two Thunderbolt 3 (USB-C) ports with support for:
Thunderbolt (up to 40Gb/s)
USB 3.1 Gen 2 (up to 10Gb/s)
If you want 4 usb 3.2gen2 ports, you'll need an imac pro
Huh? There is no 3.2 gen 2, and the iMac and iMac Pro have the same 3.1 gen 2.
Their site doesn’t make it clear. Technically there is no USB 3 anymore it’s either 3.1 Gen 1 or Gen 2.
Their site clearly states 3.1 Gen 2.
--- Post Merged, Apr 27, 2019 ---
It's been announced but not in any shipping product yet.
--- Post Merged, Apr 27, 2019 ---
I do not see it state anywhere that it is 3.1 gen 2. It just says USB 3. It states the thunderbolt can support USB 3.1 Gen 2
Yes, the 2 Thunderbolt 3 USB Type C ports support 3.1 gen 2, not the USB Type A ports.
So the 4 x USB 3 ports are Gen 1?
It is very unclear. It says USB 3. Doesn’t say if it’s 3.0 (which the term doesn’t exist anymore),3.1 Gen 1 or Gen 2.
Yes it does:
USB 3.1 Gen 2 can transfer data up to 10 Gbps. Newer Mac models with Thunderbolt 3 (USB-C) ports support these speeds.
Only the TB 3 USB Type C ports are 3.1 gen 2.
All the Apple specs say USB 3 (same as saying USB 3.0). That is a standard will exist for ever - standards never die, they just become superseded.
USB 3 is very similar to the USB 3.1gen1 and USB 3.2gen1 standards, just not quite the same. All are up to 5 Gb/s and backward compatible to USB 2.
The 4 big USB-A ports on the iMac are USB 3. And will work with devices quoted as being USB 3.1gen1 as well as USB 3 and USB 2 (or even older).
The 2 smaller USB-C ports can use either Thunderbolt 3 (40 Gb/s) and USB 3.1gen2 (10 Gb/s).
Note that USB-A and USB-C refer to the standard for the physical design of the port. USB 2, 3, 3.1, etc. refer to the signalling and data transfer standards. Have a skim read of https://en.wikipedia.org/wiki/USB_3.0
Thank you. Explained perfectly.
I find it slightly annoying how the regular USB-A ports seem to be USB 3.1 Gen 1 (5Gbps) instead of Gen 2 (10Gbps) in 2019.
The coffeelake chipset used (most likely a Z390 model) can natively support 6 USB 3.1 Gen 2 10Gbps ports (which would easily cover the 4 USB-A ports, internal SDXC card reader, and webcam) in addition to up to 14 USB 2.0 ports for everything else (e.g. internal microphones).
If Apple just made the USB A ports Gen 2 speed this would save us having to ‘waste’ a thunderbolt port when connecting a fast USB SSD for best speeds.
The 2019 iMac as a whole seems great but little details like this, where the full potential of its components is not used, irk me.
They could have easily upgraded the port without changing anything to the iMac
What needs to be done to resolve this question:
First, we need someone who has one of the new 2019 iMacs.
That person will need a USBc 3.1 gen2/nvme enclosure that has an nvme SSD inside.
Then, run a speed test on the drive connected to the USBc port.
Then, repeat the speed test with the drive connected to a USBa port.
How do the results stack up?
It is the same with the SDXC port on the 2019 iMac. It is a UHS-1 slot, only the 2 year old iMac Pro is a UHS-II slot. WTF Apple??
Z370 boards can support 9th and 8th gen cpu’s. May need an Efi/bios update so most likely that apple updated the firmware in the iMac to support the cpu’s without changing the chipset or anything else so literally bare min change to the system.
Hence why nothing else changed
The 2019 iMac is the first iMac to use the 300-Series PCH. The 2015 and 2017 iMacs used a Z170 (100-Series) PCH. At the present, I am not sure anyone knows which exact PCH Apple chose for the 2019 iMac. The Z370 PCH does not support USB 3.1 Gen 2, but the the Z390 PCH does support up to 6 directly off the PCH, which would have been nice for Apple to have supported by repacking the Type-A port with Type-C ports. I suspect that would confuse typical consumers thinking they were Thunderbolt 3 and so they opted to leave them as Type-A.
EDIT: To clarify, the 100-Series PCH does not work with 8th or 9th Gen CPUs. Apple may have chosen the C246 PCH (server Z390) as it chose the CM246 PCH for the mini.
Now would adding a USB Hub to the thunderbolt 3 slot to add additional thunderbolt 3 ports slow down that port or would all the extra ports on the hub be able to run at full speed?
Thunderbolt 3 connects multiple devices using a daisy chain (like Firewire). So hubs have, at most, 2 TB3 ports - one to connect to computer and one to connect to another TB3 device. The iMac is limited to two daisy chains. Arguably the best hub (without space for disk drives) is the Caldigit T3 Plus - this adds two USB3.1gen2 ports as well as slower ones.. The USB ports should not slow down the TB3 daisy chain except that you are limited by the 40 Gb/s of TB3.