I just got back from dropping off three monitors (two big and bulky, the third doesn’t work), two PC boxes (one works: a friend was upgrading so I offered to get rid of the old one, the other doesn’t even turn on any more), two keyboards, a 9600 baud modem, an old router, and assorted associated cables, at Free Geek Vancouver, a lovely organisation that cheerfully takes computer hardware, working or not, obsolete or not. They reuse what can be reused (installing Ubuntu + software and donating to a good home), and recycle what can’t be reused.
Reusing or recycling old computers doesn’t solve all the environmental problems caused by the computing industry but it’s at least a start.