Adding RAM barely changes your temps.

Negligible. The increase is usually 1–3°C at most.

RAM modules don’t generate much heat on their own unless you’re overclocking them or pushing voltage. When you add more sticks, you’re adding more chips that produce heat, but you’re also increasing surface area for heat dissipation. The net effect is tiny.

In a typical desktop with decent airflow, you won’t notice a difference in CPU or system temps. Even in a cramped ITX build, the extra heat is minor compared to your GPU or CPU cooler. The bigger temperature swings come from ambient room temp, case flow, and whether your cat is blocking an intake.

Unless you’re benchmarking memory at 1.5V inside a hot case, just install the sticks and forget about it.