Will Intel E10G42BTDA work with a crossover cable between 3 servers?

Maybe. You'll have to do some additional setup on each computer, so each computer passes through packets.

I'd only attempt this with Linux, if drivers are available for Linux. You'll likely be pulling out your hair with Windows.

Much simpler to just use a switch + plug all 3x computers into the switch.

I only want to connect 2 computers.  I need the faster speed for backup.  Why won't it work with Windoes server 2016?

Probably won't be faster.
Each switch port is its own collision domain and the switch has built in buffering in case of a buffer overflow.
So it's gonna be as fast as the limits of what the hardware allows.
I see no reason other than a lack of a gig switch for doing a direct connection.
You may want to set up jumbo frames if speed is what you're looking for.

Thanks to all.