when i apply a dds texture to my model, some of the back faces show through the model when rendering ingame. When i apply a bmp of the same texture to the same model its fine.

Could u please tell me wots goin on?

the dds texture has an alpha channel

i know that but its not transparent at all. it jus renders random backfaces ontop of the front ones

As Michael Schwarz said. Remove the alpha channel and you'll be fine.