What liquid/mix are you using?
Plain distilled water is the best*, but some additives may be necessary to reduce corrosion or inhibit fungal growth.
When additives are used for the above reasons, or to add color, the smallest amount possible to be effective for the purpose is best: the more additive used, the less efficient the water will be.
Is there much airflow restriction for air to get into or out of the case? Airflow is hurt by too much "stuff" in the way- case front bezels, the built-in "fan grills" in most cases, etc. This can help quite a bit in some instances. (My main machine has a front door which blocks rad airflow- when I open it, temps go down quite a bit.)
How high are the ambient (room) and case temp?
A hot room will still make the system run hot.
If your case doesn't have enough airflow the system will aslo get hot.