confusing compute shader results

I have a compute shader that generates only positions for my geom shader to build cubes. The compute shader has 4 by 4 by 4 threadGroups and a group size of 1 by 1 by 1. So there are 4*4*4 positions 'calculated', but even if i set the position for all the buffer elements to (1, 0, 0) i see more than one cube (thats been rendered on each position) on the screen, means that there are strangely come in different positions?! If i hardcode a fix position in the geom (or vert) shader the problem is gone so it has to be in the buffer/compute shader. I simplified all of the code but can't find the problem causing this odd behaviour. Anybody got a same behaviour or can tell what's happening?