If the fins cover the entire vent area then I would have to agree with mightywiz the air is pulled in from any opening it can find which is not optimal compared to intakes on the bottom of the laptop. Another cost cutting move I assume.
HP Forgot to make the vents hehe!
AMD's don't cool, they just burn up and die hehe! I have a pile of dead AMD's to prove it, hehe, just kidding. I don't want the AMD police to come and assassinate me.
I agree with mightywiz and what john is saying here, along with Brian's assessment, it makes not sense that air pulls INTO THE INTAKE, it is simply pulling air from what areas it can, area's that HP Deemed enough to cool it.
It's very clear the fan is pulling air from the top where the opening is, same as all fans I've seen, so that also coincides with what Brian and mightywiz are saying about the keyboard, and more so to one side.
I ran into something similar about a year ago, when I didn't know they were making passively cooled cpu's, and was looking all over for the intake and not hearing a fan lol.
It still amazes me at how horrible these cooling devices are on all pc's that I've looked at. I fancy myself as a bit of a backyard engineer, and the design of the cooling on almost all pc's is horrible, and done cheaply as possible. For starters, Number One on the list, would be to never Push air through the heatsink, but draw it through. I suspect on a laptop it is just very difficult to do something like this, but I've seen this on desktops also, where it would be very easy to do this.