Btw what is meant by efficiency exactly?
Yeah! That efficiency reading is nonsense, in part, because it is not defined.
I believe it is how much electrical energy ends up in the air, so in principle fans could achieve the same objective with much less power.
Electrical energy ending up in the air? Sorry Shrek but that (and the review for that spec) makes no sense. What even is electrical energy in the air? To me, it is static electricity - as in lightning or ESD.
Efficiency is a ratio of output vs input. What's the input here? The amount of air being drawn in? If so, no way is 90% being blocked. The output side of the fan would have to almost be a closed door.
So is the input the amount of electrical power being consumed (as in watts)? The review does not say but even so, what is the conversion factor of watts to CFM? I am not aware of any.
IMO, the concept of static pressure
for PC case cooling is nearly as nonsensical. Why? Because case cooling is all about creating a "
flow" of air "
through" the case. And that typically is achieved by having both intake fans pushing air in AND exhaust fans drawing air out
at near equilibrium. Even if no exhaust fans, there are vents allowing the air to vent out.
"IF" there is too much pressure inside the case then
THE USER HAS FAILED to properly configure case cooling - not the fan. It is the user's responsibility to set up case cooling, ideally with a
SLIGHT over (positive) pressure to ensure all air coming in, only comes in through the designated (hopefully filtered) intake vents. It is also the user's responsibility to maintain good "cable management" and drive placement to minimize impacting that desired "flow" of air "through" the case.
WAY WAY too much emphasis is put on static pressure
when it comes to computer case cooling. In other applications, static pressure matters. But
not in PC case cooling. Downward firing CPU and GPU coolers, as examples, require fans with good static pressure ratings. Case fans do not.
Too much pressure inside a case is counterproductive. It restricts the desired "flow" and that creates pockets of stagnant (and heated) air. NOT GOOD! So again, just "slight" pressure so dirty air is not sucked in through ports and every other crack and crevice, yet a nice flow is created to effectively move heated air out.
Who cares how fast a case fan spins? A faster spinning fan is NOT a factor in quality and not necessarily a factor in cooling. It is all about how much air the fan is moving, as in CFM. And that depends on blade design, blade width and blade length - and finally RPM.
When selecting a case fan, obviously, if the space is designed to support a 120mm fan, you don't buy a 140mm for that spot. Most case fans are 25mm thick. If your case will fit a thicker fan without interfering with other parts of the case or nearby components, you might consider getting one. Then I look at CFM and noise levels. I HATE FAN NOISE so noise matters to me.
The general rule here is a larger fan can move more air at the same or even lower RPM than a smaller fan. Another general rule is slower spinning fans make less noise than faster spinning fans. And yet another general rule is two fans spinning at slower speeds can move more air while producing less noise than one fan spinning at full speed. Because I HATE FAN NOISE, I will not hesitate to spend extra on two fans, instead of one faster spinning fan.
Are there exceptions, of course. But exceptions don't make the rule.
Another rule is this - cost does not determine the best fan.
Oh, and a quality case goes far to suppress fan noise too.
I only mentioned the word "case" 17 times, and the word "flow" 4 times in my last reply. Sorry you still did not pick up on, or understand that. 
