Soldato
I'd flog the 3090 Ti, use the money in a couple of months to buy a 4080 and keep the change. Should be around 40-50% faster than a 3090 Ti and more power efficient. Skipping a generation with a massive leap in performance doesn't make much sense, that 3090 Ti with loads of memory won't look nearly as appealing when it's getting demolished by new GPU's and electricity prices are through the roof.
I'm not getting it for another 2 months by which time the 4000 series will be out which will quite likely be a lot more expensive than what I'll be paying and electricity won't be a factor really as my main game is FF14 which I limit the FPS to 60, The card will practically be asleep XD