Quickest -

1. Take the lid off the source PC put the HDD in it
2. Copy the stuff.
3. Pull it out
4. Put it the other PC,
5. Your done

Formatting the HDD my be optional.

Connect both computers over ethernet and rsync the data across. It will still take several hours over gigabit ethernet though.

1. Take the drive from PC 1 and attach to PC 2 => copy / paste

2. External drive

Parallel port would be faster than serial, but if you’re using serial I’d go with Z modem for the compression and error correction.

I just transferred 12tb from one hdd to another via usb 3.0. Went at roughly ~180mbps and took 1.5 days

rsync over a wired network. That way, I can stop and resume at any time.

You could go over a wired network.

I have a PC in a spot of my house I can’t get a cable to. But that’s the PC I do my Blu Ray ripping and encoding on, so I keep a 5tb external drive for moving the files to my NAS afterwards. Sometimes it would take days over WiFi instead of minutes to hours over USB 3 twice. (and piss off my wife for saturating the wifi, heh)

USB 3.1 Gen2 is hard to beat. 10Gbps. But for HDDs the HDDs themselves will be the bottleneck. For sustained file transfers, perhaps no more than up to 3Gbps, even if installed in the same PC. Good SATA SSDs may manage closer to 6Gbps. NVMe SSDs are likely to saturate USB 3.1 Gen2. Then PCI-e directly between installed drives is the fastest. Normal cabled network is only 1Gbps.

File transfers to/from external multibay USB DAS can be done in parallel, involving multiple HDDs, and come close to saturating 10Gbps USB3.1 Gen2 speeds.

Then there is thunderbolt.

Start a rsync transfer when you go to bed. In the morning it will most likely be done.

robocopy or rsync if you can’t place the drive in the target or an external enclosure.

External usb hdd

Over LAN with flavored solution of your choice.
Other than that, I use one of my spare drives and my USB docking station if I need to move it outside of my own house. I never really had a need for dedicated external drives but a docking station is handy for many things, this being one of them.

If you want the bare minimum fast transfer and both PC are in local network, use Dukto-R6. It’s super basic file copying, you just need to drag and drop.

For more advanced options,the others have already pointed it out.

Shouldn’t actually take too long… I’d just take a couple sata cables. I transferred 6tb in about 12 or 18 hours, idr.

Fastest “normal” way would be write it to a USB 3 drive on machine 1, read from drive later on machine 2. An SSD would be best. Even with having to do the write and read in two phases, I’d still expect it to be faster than a 1G network.

(Less normal ways would be things like Thundrerbolt SSDs, 10G or 40G ethernet for direct transfer, etc. But if you have that kind of tech already in place, then you’re not asking. ;)