Originally Posted by axipher
The shrouds help in preventing dead spots on the RAD surface.
This translates to better heat removal at the same fan speeds, or the same heat removal, with slightly lower fan speeds. It's not as noticeable on the H100, about 1-3 degrees, but on higher end rads, it could easily make a little more of a difference.
I just prefer how much lower I can run my fans and still get the same cooling performance.
I tend to agree with this. Ive always found the use of shrouds to be helpful in lowering the temps in my old H50 and H100 by about 1-5c, depending on the fan speed. Im using AP-15s in push/pull (intake).