Unfortunately at this time, we do not support adjustments of your GPU or CPU's usage. This is because some parts cannot be adjusted, such as system RAM, or GPU VRAM usage. This is a basic requirement of the miner, and cannot be changed or lowered.
Something that can be lowered however, is the core usage of your CPU or GPU. This is something that we may introduce as a feature in future versions of Salad, however currently there is not a system in place to support this.