DC is the only way to go when controlling the speed of your PC fans . I bought mine at Rad Shak so I know they have them...they told me they didn`t have them either . You have to deal with kids that don`t know what their doing most of the time...so do your research before hand . When I found the area at Radio Shack that had what I needed I found several types to choose from . DT Wilm. Ohio