Older GPUs still have an active secondary market but they are probably not profitable at market rates for inference because newer chips are so much more efficient.

If Semi-Analyses is correct [1], even H100s would lose money at current prices - I doubt that is actually true of H100s in practice because from what I can tell it is based on a 3-year depreciation from the new price, but the point is that there is a point at which old hardware's operating inefficiencies dominate.

https://inferencex.semianalysis.com/infx/profit-estimator/de...