I know that CS GO can only go up to 299 fps. But is it any possible way I can bring it way more down, to like 60, because I dont want to use all my processing power on 299 fps...?
You first need to enable the 'developer console' in game options. This is opened using the key to the left of 1 key (grave accent on GB keyboard).
You then type
fps_max 60 but it is important to remember that v-sync is your enemy as it creates an input delay by artificially matching your frames to the refresh rate of your monitor (always off).
In regards to wasting processor power, it's more about excessive heat for your graphics card by producing unnecessary frames that your monitor cannot replicate.
Check your monitor as to whether it is 60hz or 120h or even 144hz as you should match your fps_max setting to this figure for the smoothest experience.
For competitive fps, 120hz+ is superior.