front or rear case fan

[olds442]

should my case fan be in the rear or the front? my PSU has a fan the blows hot air out along with my GPU.

[Rob52240]

Either or, if you have more than one fan mounted on different sides of the case you should mount them so they suck and blow.

[perdue3]

suck and blow.

Ha

[Bizman]

Usually it's best to have the fans blow air out. Fans that blow air in are for the most part used to direct the airflow to a desired point.

Although both your PSU and GPU blow out, they produce heat themselves, thus also heating the inside of your case. Putting an extra outbound fan as high as possible will make cool air flow all through your case, cooling also your RAM sticks and HDD's. In a good case there are a lot of ventilation gaps for the intake, in better ones even with dust filters, so there is no need to force air in.

[Drano]

I have a cm-690 II advanced case. Love it. Airflow is great and you can put up to ten fans on it. BTW my setup is fans in on front, bottom and sides and out on top and back. Remember heat will want to rise so might as well help it along.

[The Fugitive]

Personally I like to have an equal number of fans blowing air in as blowing it out. The reason is if you have more fans blowing air out your creating a vacuum to draw air into the box.

Two reason why I think that's bad. First air coming in should be filtered. Some of the newer boxes are starting to add filter that keep bigger particles out of your machine. Drawing air through all cracks and holes in your box would be by-passing these.The second reason is the air drawn in by vacuum doesn't have any real force and so all the "crap" that is brought in can easily just drop off the air currents and land all over you components in the box creating hot spots that are not cooled due to being "blanketed" by dust.

By having equal forced air in and air out you maintain a strong air flow keeping the chance of dust settling at a minimum. Most piece of equipment will draw air in from the front low, and blow it out in the back high (warm air rises, cool air is lower). I even plan on adding a fan and hose to direct the warm air out from under my desk as the computer box is under the desk on the side wall (wife ack says no crap on the desk!). 

[Bizman]

Fugi, you have a point in your argumentation. I've seen computers that look like they grow hair in every crack due to stuck air intake holes.

Which cooling method works best depends much on the design of the case.

On my case the front panel is made of mesh with a filter behind it. Even the dummy panels for extra 3.5/5" devices are made of that mesh. There's absolutely no way to prevent air from flowing through the whole front panel. At the other end of design are the old Power Macs, which had two tunnels through the entire machine with fans at both ends, coolers along the way. So my case works best with negative pressure and the Mac type with even pressure. In very dusty environments a pressurized case with fresh air coming from a cleaner place would highly probably lengthen the computer's life span

[Masherbrum]

What case do you have?   I have modified my already cool Tempest and made it cooler with fan upgrades.

[Bizman]

I have a CoolerMaster Centurion 5 which I bought about 5-6 years ago. There's one 80mm fan for intake and one 120 mm for exhaust. Every once in awhile I use the vacuum cleaner on the front mesh.

[Rob52240]

The idea is to draw fresh air into the case to pick up heat and then exhaust it to take the heat out of the case.  Just like any other air handling device that's been designed by someone who knows what they're doing.  Creating positive or negative pressure inside the case has no benefit.

[Rob52240]

.

[Bino]

should my case fan be in the rear or the front? my PSU has a fan the blows hot air out along with my GPU.

I have a Lian Li "Armorsuit" PC-P50.  Stock, the case comes with one 120mm intake fan mounted low on the front, an air intake in the case for a bottom-mounted PSU, two 140mm case exhaust fans on the top, and a 120mm case exhaust fan mounted high on the back.  I added a second hard drive cage/fan unit, so I have two 120mm case intake fans on the front.  The covers for the front intake fans and the bottom PSU intake have washable dust screens.

Even with three exhaust fans, there is enough flow from the two intake fans that there is air coming out the vents near the expansion slots, low in the rear of the case.  And since each of the fans spins at only ~2000 RPM, the system seems pretty quiet to me.

[Dragon]

should my case fan be in the rear or the front? my PSU has a fan the blows hot air out along with my GPU.

As much as you suck, your case should blow.



Just sayin

[hotard]

My case is a cooler master haf 922, and  has 1 200mm (lower front) intake fan, and 1 x 200mm (top) and 1 x 120mm (upper back) exhaust fans. The power supply  has its own fan that is drawing air from under the case, so all in all it's about equal intake/exhaust

[2bighorn]

Creating positive or negative pressure inside the case has no benefit.

Positive pressure prevents dust coming in the case through unfiltered slots and prevents heated air from re-entry into the case. It also helps with cooling the GPU, since most of the cards have exhaust slots in the rear and intake inside the case. Positive air pressure helps with air delivery to GPU fan.