Here's a little tool I cobbled together that some of you may find handy, it's a TGA/PNG (and others?) to DDS converter, there's a readme file inside giving directions, also don't worry, it's free, just put in 0 and submit. This is great if you don't want to deal with imaging software to do conversions for you, or if you have to convert a lot of image files at once.
I know using batch files and registries can be concerning but it's safe, you're free to ignore this otherwise.
Happy converting.
https://gum.co/GYPCX