How grilles affect CFM?

[MonkeyFaces]

Here are my fans and their grilles
80mm above pci slots, grille on case
120mm rear, grille on case, wire grille on opposite end
120mm HD, grille on case, wire grille on opposite end
120mm CPU, Wire grille on top of HS
120mm PSU, same grill placing just about every psu has

Do grilles interfere with CFM? I have heard that cutting out the hole grilles on most cases and replacing them with wire grilles will improve CFM. Should I be worried about the grilles that I place on the opposite ends of my fans? They keep stray wires from making noises and just look damn cool. Do they interfere with CFM enough for me to take them out? How much cfm do I lose when there is a grille on both sides of a fan?

 

[996GT2]

If you have the standard grills (they look like this: http://www.watercoolingshop.com/catalog/images/80mmgril.jpg, then you shouldn't be worrying about anything. Those won't mess up airflow much at all. However, if you have mesh grilles like this (http://lib.store.yahoo.net/lib/directron/BlackFanGrillMesh2.jpg all over your PC, then you should remove them and replace them with standard grilles. You don't need grilles on the inside of your computer, just on the outside. However, if you just have standard grilles on both sides, it won't be much to worry about.

 

[Zepper]

Grills on fans inside the case keep wires and fingers out of the fans. If you tie all your wires down and are careful with your fingers, THEN you don't need them...

Some cases come with very restrictive grilles punched into the case metal (see pictures of most Skyhawk cases for a bad example). Those should be cut out and replaced with wire grills which are the least restrictive type.

.bh.

 

[AyashiKaibutsu]

What are your fingers doing in the case while it's running to begin with?

 

[Zepper]

What's life without risk?

.bh.

 

[Bluefront]

It's easy enough to test this out. Take a fan hooked up at a set voltage, with no restrictions on either side......measure the rpm. Then screw a wire grill on the fan and run it at the same voltage. The drop in rpms will give you a percentage, which compares well to the drop in cfm.

While every fan will suffer a slightly different percentage drop, from what I've heard, wire grills cause about a 12% loss in cfm. Check it out....

 

[LOUISSSSS]

i have one of those mesh grilles on the top of my case and it blocks off about 50% of the airflow...

 

[Silmatharien]

I took most of the grills out of my case. I figure it can't hurt. I don't work on my computer that much when it's on anyway.