256x256 Cubemaps look weird

[Unicake]

So I tried increasing the texture size of some cubemaps in my map, but there are white outlines on the edges of the reflection.

Is there a fix to this or is this why high cubemaps shouldn't be used?

 

[henke37]

Could be a driver error. Have you tried building them, and testing them, using the software renderer?

 

[Unicake]

How does one use a software renderer