bank conflicts

Why is it that there are no bank conflicts between different half-warps, but only within a single half-warp.

Section 5.1.2.4 of the programming guide (version 1.1) explains that memory requests for the first and second halfwarp are independent of each other.

A memory access takes two clock cycles, which is the execution time for a half-warp, as a full warp takes 4 cycles.

However IIRC there was a warning somewhere, that in the future you might have hardware that cann actually process the whole warp in those 2 cycles, then you could get conflicts in between the half-warps, too.