I have a rig with one RX 550 4 GB, one HD 7950 3 GB and one R9 290 4 GB. All mine ETC 59 MH/s @ 398 W at the wall (measured with power meter).
Also it's an 850 W PSU, only bronze rated.
RX 550: 11.35 MH/s
HD7950: 24.46 MH/s
R9 290: 23.13 MH/s
I'm trying to buy older AMD cards because they are really cheap and still profitable, if you known how to config them.
Weird that HD7950 is higher than R9 290, i think it should be close to 28-30Mh/s
the good old days has been passed, well 2012 card still mining in 2021, the power is to wild for greener mining this days

surely the cards still able to makes some bucks, these veteran gpus already mining since first crypto mining sha256&script, better to put them on museum