The detachment of ribs configured for inducing strong secondary flows is a possible concept for 'artificial roughness' designs in cooling channels to enhance heat transfer with a lower temperature spread on the thermally loaded channel walls as occurred for fully attached ribs. The present study reports on the effect of wall proximity of detached 60 deg upward directed V-shaped ribs on the convective heat transfer in a square channel. The results obtained from large eddy simulations (LES) showed that the convective heat transfer depends on the wall proximity of the detached rib. It was increased compared to attached V-shaped ribs, and a homogenization of the local Nusselt number distribution and the surface temperature occurred due to the avoidance of pronounced recirculation region in the rib rear with significant temperature peaks.