There might be a few reasons why your GPU isn’t being used to its maximum potential. Of course one reason is that you aren’t dong anything that requires full GPU power, such as web browsing or playing video games at a capped fps. However, there are instances when a GPU can’t or won’t output it max strength even when asked. One of them would be electricity.

Perhaps your graphics card (GPU, in this case) requires more power than your Power Supply Unit (PSU) can output. For example, lets say you have a 400 Watt PSU and you have a higher-end GPU that requires 450 Watts. Your PSU wont be able to run both your Motherboard and your GPU, so your PSU prioritizes your motherboard first, and is only able to give your GPU 300 watts. Likewise, your GPU now only has enough power to run at a little more than half speed, because processing power requires electricity.

Another reason your GPU might not be fully utilized is that your PC is on some kind of Power-Saving mode. This is especially prominent on laptops, but it can still happen on desktops as well. In this case there might be a setting to improve the life on a battery by reducing the amount of power consumption by certain aspects of a computer. GPU’s are notorious for being extremely power-hungry, especially now as you see that more than half of a gaming rig’s power requirement comes from the single component. And your windows or whatever you are doing knows this. So, when this setting is on, it soft limits the amount of power your GPU is allowed to take. When on battery power, this elongates the battery’s life, however when you are using standard electricity from a wall outlet all you are doing is limiting yourself. If this is the problem I would try and turn it off, as I think its more useless than useful (it is useful when I need my battery power, but that’s only 15% of the time)

So yeah that’s about it, try and figure out for yourself if you need more power or something. That’s the main reason I have seen for this type of problem.