A MagnetoHydroDynamic (MHD) problem is numerically investigated in the framework of this research work. An Fe3O4-Water nanofluid is filled within a specific pseudo-square enclosure with a semicircular heat source at the left-hand wall of the enclosure (hot temperature) as well as a sinusoidal imposed temperature (based on cold and hot temperature evolutions) at the right-hand wall. The remaining walls are supposed adiabatic. The mathematical model of the MHD problem (continuity, momentum, and energy conservation equations) is elaborated under specified assumptions related to the real physical problem. The dimensionless form of the MHD problem is constructed. The coupled effects of Rayleigh number, Hartmann number and heat source radius on thermal (in terms of isothermal contours) and flow (in terms of streamlines and velocity magnitudes contours) behaviors of the nanofluid are numerically investigated. In addition, the effect of Rayleigh number on the evolutions of nanofluid velocity magnitude and temperature is investigated among the vertical direction X=0.2. All the numerical results are clearly presented, discussed and interpreted.