I play WoW off of my HDD, personally. If you have no space on the SSD, you either have to remove something else to make room for WoW, or move WoW to an HDD. It probably is slower, so if you prefer SSD load speed you should try to avoid it, of course.
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I meant to say E:\, no idea why I said C. Obviously, just replace the letter with whichever drive you are using. My bad.
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He was asking how to move WoW to an HDD, and I assumed he wanted to save time and/or bandwidth; that is how to install WoW quickly with minimal bandwidth. I was assuming that space on his HDD isn't an issue, as well. Which is a reasonable assumption, I'd think.