Bottom and side fans - any point?

[samion]

Hi I'm very new to cases and fans (have always just built systems without fans) btu am now building an OC 2700k system with a 6950 GPU so will need somethign cool.

I've done a LOT of reading and researching and ppl here have been very helpful so far (thank you!! ) and now I have three questions.

1) Bottom fans - are these better than front? Or are they pointless? It seems front is most popular but some cases go bottom and top instead of front/back, which really makes more sense seeing as heat rises etc Is this the better way to go?

2) Side fans - good or bad? I'm interested in a Luan-Li (p63) case which looks awesome excpet for one thing - no side fan hole !!! One of the many things I read (somewhere) says that airFLOW is the most important, so one shoudl keep it simple with air entry at the front and exit at the top and therefore having a random gust of air blasting in from the side just destroys the air current and confuses things... is it nto a good idea? is it ok? or is it very important? and if so, can I just drill a load of holes in the side panel and pop my own fan in?

3) More vs less fans... I'm beginning to think after some help here that more fans at lower RPM will help me shift as much air but will be overall quieter than a couple of fans at the higher RPM. Any thoughts?

Thanks for any help in advance

 

[Automata]

The direction of airflow isn't as important as getting hot components cool and air evacuating it as quick as possible. The temperature differences that we see in a case aren't large enough to get a good force by itself. A very low speed fan could easily overcome the pressure of heat rising in a case. For the purposes of desktop computers, you can disregard this.

Placement of the fans is important only to the point of my first comment. If you just put fans wherever you want and don't think about where it is routing the air, you will only get lower temperatures by luck.

For example, I'm running a Cooler Master 690 Stacker case, which can have 4 fans in the door. To get proper airflow, these fans are aimed in. The back fan is out and the front fans are also out. I do this because the front fans would be fighting against the door fans and would decrease the overall airflow.

You will have to consider this on a case by case basis since they are designed differently. So, to answer your questions directly:

1) They can be good if they are in a good place. Most on the bottom are right up against the power supply, so the wiring will likely be blocking some of the airflow. The placement can be good, especially if you have a video card that pulls in air at the end and pushes it out the back. Another thing to consider is dust. If this system will sit on the floor, it will pull an incredible amount of dust from the bottom fan. Id you have it off the floor, this will mitigate the effect.

2) This is the same answer as 1), except you likely won't have wiring blocking airflow.

3) Placement is more important than numbers.

 

[samion]

For example, I'm running a Cooler Master 690 Stacker case, which can have 4 fans in the door. To get proper airflow, these fans are aimed in. The back fan is out and the front fans are also out. I do this because the front fans would be fighting against the door fans and would decrease the overall airflow.

This makes soooo much sense I can't believe it's not standard! Why not blow air directly onto everything from the side and let it escape from the edge rather than draft it in obscurely through the random front bottom corner. Brilliant! I might have to rethink what I do. Why is this not far more commonly done as I've not heard of it before ! ?

 

[Automata]

The door panel is pretty annoying to work with. I can also only use 3 fans because the fourth one will hit my heatsink (Thermalright Ultra 120 Extreme).

Because of the fans, they use a mesh on the door, which attracts a sheet of dust that I have to clean often.

 

[grumperfish]

I keep an aftermarket 250mm side fan on my Armor full-tower as it makes sure the board and RAM stays cool. If I wasn't using a comically-massive CPU cooler it probably wouldn't be as necessary, but it's good insurance.

 

[Knufire]

Side fans are usually only found in gaming rigs like the things people build here, as it provides a direct flow of cool air to the major components.

Typically though, if you have a front intake and back exhaust, that's should be sufficient. Another front intake and a top exhaust would be preferrable. I'd only use side fans if you have multiple HOT GPUs that would want the direct airflow. But that's only me personally, as I'd rather have a clean window.