What is heatsink shroud for?

[Omnirizon]

I've seen some things called heatsink shrouds. it looks like they cover part of the heatsink. They only seem to be a part of factory builds like Dell and HP. don't these things reduce airflow through the fins? or do they serve to focus airflow (via Newton's Second Law [I think] which would cause air to speed up as it went through a narrower area in order to conserve energy)? well, I'm not too savvy on physics, but I think that's the idea.

any clue?

 

[Conumdrum]

Yep, exactly that. HP and Dell cases are known for smallish cases and waek cooling systems. Su adding a shroud to help direct airflow where needed is common.

In an enthusiasts case where a massive CPU HS is used and there is plenty of fans it's not really needed.

I have seen many many home made shrouds in a case to do the same thing, it's something peeps try if they have issues. Sometimes it helps, sometimes it's just fun to read about their adventures with cardbard and duct tape.

 

[Bluescreendeath]

2nd law:
F = M*A ?

 

[idontcareenoughtomakeitclever]

the 2nd law is m(dv/dt)=F or mv=M which can be used to derive conservation of energy or momentum (or mass flow rate). he's right about 2nd law, but wrong on application anyway