I will discuss recent work on using the X-ray and optical properties of a sample of 318 radio-quiet quasars to investigate the dependence quasar accretion disk structure on black hole mass and accretion rate. Specifically, we studied the dependence of the ratio of quasar optical flux to X-ray flux on black hole mass and Eddington ratio, as well as the dependence of the X-ray spectral slope on black hole mass and Eddington ratio. We find evidence that quasars emit a smaller fraction of their bolometric luminosity in the X-rays as black hole mass and accretion rate increase. In addition, we find evidence that the X-ray spectral slope displays a non-monotonic dependence on black hole mass and accretion rate. I will discuss our results within the context of accretion models with comptonizing corona, and discuss the implications for quasar feedback. This work was supported in part by NSF grant AST03-07384.