zinny as stated, it's not a REX or texture issue. 

 

@FlightSimDimm, it does help in some instances. Depends on the severity of the problem.

It's not the cloud textures, it's the way the clouds are displayed (FSX/P3D issue). Because REX4 uses HD clouds, they are more 'distinct' in their appearance and so repeating clouds are more evident. Soft Clouds would look better, as they are less distinct in appearance anyway, but again that is missing the point.

 

Novation explains it the best:

 

http://forum.avsim.net/topic/458467-rex4-and-fsx-popcorn-clouds/#entry3142619

 

asanal's image is really obvious - the cloud layer is very thin; the way FSX/P3D basically displays the cloud is to upscale or downscale individual cloud textures based on height (roughly), so the thinner the cloud band, the more repetitious the cloud textures in order to provide the same octa coverage. If you use thicker clouds, it is less prominent.

 

Conversely, perhaps try a stratus cloudset, rather than a cumulus - stratus or stratocumulous clouds are wider than taller and helps with the tiling effect. (although stratus cloud sets exacerbate the spinning cloud issue, for the same reason).