The present work first submits to investigation the non-Oberbeck-Boussinesq (NOB) effects in a tall water-filled differentially heated cavity by means of direct numerical simulations. The results reveal that if NOB effects are considered, the flow is no longer symmetric as the transition point moves downstream on the hot wall and upstream on the cold wall. Afterwards, the assessment of the large eddy simulation models is performed in order to test their capabilities for not only capturing the complex phenomena like transition to turbulence, turbulent mixing, and interaction between the boundary layers, but also for reproducing the NOB effects. The performance of different subgrid-scale models is assessed.