well i have 4x powercolor, 2 in mine and 2 in another build for a friend.
all of em have the same prob: sometimes they freeze in 2d mode -> simple fix: just make a new profile with higher 2d settings and all works perfect.
and it doesn't make a difference if they are on water or stock. for me, it's just a driver issue and the ek's works perfect and no cold/warmbug too ^^.

mb u should try it too