IINM, those fans that come with Scythe heatsink are made to run on silent...
When it comes to silent fan, then the fan would be slow...

When it's slow, then the CFM would also be low...

That's why u can't feel any air coming out of the heatsink...

I've own a Scyhte Ninja and Scythe Mine before, and those fans that comes together with both Scythe heatsink i've used before are so silent and slow...

Even if the fan is running at 1500RPM, for 120MM fans, that is still slow...