it doesnt seem to take much more space to have 8 of them on the texture anyway
.
So finally it's only the textures saves with nvidia/photoshop as 3dc that are corrupted. Saving in dtx5 looks good , my bad. I must have loaded the 3dc version to save it as ATI2n and DTX5 im not sure.
I also tried with compressenator, adding mipmap and saving normal as ATI2n and DTX5. They both look good in game but then with ATI2n, it doesnt create mipmap or at least, they dont show up in photoshop when i use the option to view mipmap.
So In the end DTX5 seems the only format to work well and DTX5 generated from compressenator looks the best IMO.