The classical , relativistic thin-disk theory of Novikov and Thorne ( NT ) predicts a maximum accretion efficiency of 40 % for an optically thick , radiatively efficient accretion disk around a maximally spinning black hole ( BH ) . However , when a strong magnetic field is introduced to numerical simulations of thin disks , large deviations in efficiency are observed , in part due to mass and energy carried by jets and winds launched by the disk or BH spin . The total efficiency of accretion can be significantly enhanced beyond that predicted by NT but it has remained unclear how the radiative component is affected . In order to study the effect of a dynamically relevant large-scale magnetic field on radiatively efficient accretion , we have performed numerical 3D general relativistic - radiative - magnetohydroynamic ( GRRMHD ) simulations of a disk with scale height to radius ratio of H / R \sim 0.1 around a moderately spinning BH ( a = 0.5 ) using the code HARMRAD . Our simulations are fully global and allow us to measure the jet , wind , and radiative properties of a magnetically arrested disk ( MAD ) that is kept thin via self-consistent transport of energy by radiation using the M1 closure scheme . Our fiducial disk is MAD out to a radius of \sim 16 R _ { g } and the majority of the total \sim 13 \% efficiency of the accretion flow is carried by a magnetically driven wind . We find that the radiative efficiency is slightly suppressed compared to NT , contrary to prior MAD GRMHD simulations with an a d hoc cooling function , but it is unclear how much of the radiation and thermal energy trapped in the outflows could ultimately escape .