My Premiere Pro doesnt use gpu

PrPro doesn't use the GPU simply as an addition to or replacement for the CPU. It uses it for specific effects processing, especially color, warp, and other reszing things. Here's the list of GPU Accelerated Effects ... when those are not in use at the moment, the GPU may or may not get much use.

There is a completely different form of hardware/software processing, which is H.264 encoding. And has nothing whatever to do with the Mercury Acceleration settings. The hardware/software processing message you see in the Export dialog Summary section is only there IF you are exporting to H.264 ... and what shows will depend on your CPU, as some CPUs have the added hardware for 'hardware acceleration' and some don't.

Further, for any 2-pass encodes, those will always be "software" because no hardware does 2-pass encoding. Period.

Neil

Do not count on Windows to be fully up to date when it comes to device drivers
Go to the vendor site to be sure you have an updated driver for your graphic adapter
nVidia Driver Downloads http://www.nvidia.com/Download/index.aspx?lang=en-us
-for Premiere Pro and MAYBE Premiere Elements use the STUDIO driver, not the GAMING driver
-such as (this MAY not be the latest) https://www.nvidia.com/en-us/drivers/results/170344/
If you have a laptop you MAY also need to check for a laptop specific nVidia driver

There are also intermittent reports that the newest driver is not always the best driver due to driver bugs or compatibility issues, so you MAY need to try an earlier driver version