r9 290 are profitable even in 2019 while mining Ethereum on Ubuntu with version no higher than 16.04 (for GPU compatibility). Also it is profitable if you have cheap electricity while mining Beam, Monero and Zhash coins. You have to install driver version 17.40 and AMD SDK kit. There is a guide how to do it (in Russian):
https://www.cryptoprofi.info/?p=3313. It is also useful for mining on all old cards including R9 280, 290, 295 and 390.
it just works on SMOS, except the only clock/voltage control is DPM states, makes the occasional finickiness of ubuntu less of a problem. I personally used Hawaii Bios Editor to tweak the states so it behaves a bit better.
My 290's are getting between 2.5 and 2.77 on cuckarood29 with lolminer, and 28-30 on ethash. c29 is much cooler running than ethash.