Then get a modern GPU and limit the power to what your 1080 draws. It will still be significantly faster. GPU power is out of control these days, if you knock 10% off the power budget you generally only lose a few percentage of performance.
Cutting the 5090 down from 575w to 400w is a 10% perf decrease.
5090 was an example, same process applies to lower tier GPUs that don't require extra power cables. ie a 3080 with the same power budget as a 1080 would run circles around it (1080 with default max power limit of 180w gets approx 7000 in TimeSpy, 3090 limited to 150w gets approx 11500). Limiting the power budget is very simple with tools such as MSI Afterburner and others in the same space.
Cutting the 5090 down from 575w to 400w is a 10% perf decrease.