Oxide-aperature-diameter dependent analysis of RIN for high-speed, energy-efficient Vertical-Cavity Surface Emitting Lasers (VCSELs) have been performed. Small oxide-aperture diameter VCSELs are prefered for low energy consumption data transmission. We demonstrate that energy efficiency is not in conflict with our VCSELs′ RIN characteristics. The experimental results indicate that small oxide-aperture diameter VCSELs, which are the most suitable for energy-efficient, temperature-stable operation, exhibit lower laser RIN due to less mode competition inside the smaller optical cavity volume. Our energy-efficient VCSELs fulfill the RIN requirements of the 32G Fibre Channel standard. These devices are advantageous for future high performance computer applications.