I suppose it depends on the allowable temperature, CPU's need to stay around 50-70 C these days, if higher temps are allowed by the device being cooled then more power can be dissipated, depends on ambient temperature, computer cases get warm, if there is greater air flow it should be able to dissipate more
This test of several CUP coolers CPU coolers compared! measured above 0.5 to near 1.0 degrees C rise per watt. From the pictures I would guess your unit is around 0.75 degrees C/W. Thus you can dissipate 33W for a 25C rise to give a 50C heatsink temperature with a 25C air ambient.
I have to say that some of the fan coupling designs are quite laughable, I've just been looking through ebuyer, the amount of fans that just sit in air and have no shroud is baffling, to think where i work we got a radiator fan housing returned due to performance issues because there was on a 35 cm diameter fan a 1 cm larger tip clearance than specified between fan tips and housing. and yet other people seem to think that a fan somewhere on the heatsink with no shrould looks cool and will work....