Converting cheap case fans to PWM

[harshilsharma63]

hi. I noticed that two of my 80 mm non-pwm fans have a third solder point. Is this for the PWM input? If I solder a third wire here, then can the fan be operated like a 3-pin PWM fan?

*dl.dropboxusercontent.com/u/18544696/Harshil2467.jpg

*dl.dropboxusercontent.com/u/18544696/Harshil2466%20copy.jpg