The rms(E) in the 0.01–1 Hz frequency range for NICER (red) and XRISM Resolve (blue). For comparison, the black symbols show the rms(E) from NICER in the soft spectral state (A. A. Zdziarski et al. 2024). We see similar trends in soft X-rays, with broad peaks around 1 keV, although the soft-state rms is much lower. Above that, we observe a decrease with energy in the hard state and an increase in the soft state, while both converge in the Fe K energy region.