I have heard that undervolting your GPU gives more fps and lowers the temperature. Does this work and if so, how does it work?
I am thinking about undervolting to get lower temperatures on my rx 580 oc.
Undervolting only improves FPS if your card isn't maintaining it's max clockspeed due to power or temp limits. It does lower power/temps/noise though, regardless of FPS effect, which is always welcome in my eyes.
Have you ran GPUz to determine if either of those are causing performance limitations?
I helped someone undervolt their RX580 in this thread. You'll find what you need there to get started.
To paraphrase from the linked thread: Undervolting is to set the voltage for a given frequency(ies) lower than what the Auto/default values are (this applies to both CPUs and GPUs). AMD/Nvidia/Intel can't spend the time required to test and custom set a perfect freq/voltage curve for each chip they manufacture. Instead they test a bunch of chips, get a band of variance, and set a freq/voltage curve that encompasses all chips. Depending on how lucky/unlucky you got in the chip lottery, you may be able to undervolt your chip a lot or a little respectively from the stock values without changing the operating frequency.