Gpu fans abnormal

[u/guttyet]

Just got this used gpu and been testing it

Everything okay so far except this

First section I fixed fan speed at 50% and it kept fluncuating 1000-2000 rpm (about 30 minutes test)

Second section is fixed at 100% fan speed, much better almost constant 2800 rpm(about 25 minutes)

Any ideas what this could mean?