1 case fan: side intake/exhaust or front intake?

[johnny_boy]

I have one 120mm fan that can be mounted in one of two places, and I'm wondering which is better: side intake/exhaust or front intake? I currently have it set to front intake.

I also have a tower cooler with its fan pushing air toward the back of the case, if that makes any difference.

There's no discussion of this sort of scenario on the internet since most people throw in as many case fans as they can--two spots, two fans. But I'm trying to keep this thing as quiet as possible. (Of course I could experiment, but this is easier.)

 

[Dankk]

Front intake. (Assuming you already have a rear exhaust fan).

IMO, there's kind of a logical order of where you should install fans, depending on how many fans you have:

1 fan: Install it in back

2 fans: back, and front

3 fans: back, front, side

4 fans: back, front, side, top

But then again I don't claim to be an expert in cooling. Someone feel free to prove me wrong.

 

[johnny_boy]

No exhaust fan, just the cpu fan and one case fan. I would use it as exhaust except that it's too big: it's 120mm and the exhaust hole is only 92mm.

Still intake? It seems so far away from the action as to not do anything. At least as side intake, it would be throwing cool air right onto the tower heatsink, or else exhausting it away from there.

 

[Ken g6]

I would say exhaust is better. Once you have hot air, you want to get that air out of the case as quickly as possible, so it doesn't recirculate inside the case.

Though technically I imagine you have two external-facing fans: One for the case and one for the PSU. Where is the PSU mounted - bottom or top? Edit: And does the PSU have a bottom or a back air intake? Top might help suck hot air out of the case; bottom is more likely to suck in cold air from an intake fan.

 

[Dankk]

In that case (pun not intended), I suppose using it as a side intake will work. But I think you should look into getting a 92mm fan to install in the back.

 

[johnny_boy]

Hmmm. I forgot to say that the PSU is at the top, sucking hot air off the heatsink out of the case.

Perhaps I'll just experiment and see what yields the coolest temps. I'll report back with the details. First person to guess correctly which yields the coolest temps wins a virtual high five!

 

[Ken g6]

I misunderstood: You don't have any exhaust fan in back except the PSU?

You didn't say exactly what case you have. But if I had to guess, I'd say the best way with what you have would be leaving the fan as front intake and pointing the HSF and CPU cooler up at the PSU. Not only will this direct the heat up to the fan, the PSU may also detect the increased heat and ramp up its fan.

Of course, this may not be what you actually want. If the PSU is not a good brand, it may not be able to handle the increased heat, and may fail sooner. Plus its fan may be loud when it gets revved up.

If you do have a space for a 92mm exhaust fan, I'd suggest you get this one. It's cheap, it's quiet, and it's fairly good at exhausting air. It's actually the only case fan I have running in my case.

 

[johnny_boy]

I have a fractal design core 1000. Actually I just tried mounting the 120mm to the side but it bumps into my xigmatek loki, so that's not even an option! I should've checked that in advance.

I want to keep the system quiet so I wouldn't want the PSU fan ramping up. Looks like I'll leave everything as is. I'm idling at 28C and just over 50 under load. I was hoping to get temps down a few degrees so that fans don't ramp up under load (which they sometimes do). Maybe one day I'll invest in a pwm exhaust fan.

Thanks everyone for input.

 

[Idontcare]

Front intake. (Assuming you already have a rear exhaust fan).

IMO, there's kind of a logical order of where you should install fans, depending on how many fans you have:

1 fan: Install it in back

2 fans: back, and front

3 fans: back, front, side

4 fans: back, front, side, top

But then again I don't claim to be an expert in cooling. Someone feel free to prove me wrong.

I like this, it is my rule too, except I'd make one change to the "3 fans" rule which is I'd put a fan at the top (exhausting, of course) before I'd put a side fan on.

From an air-flow standpoint side-fans are totally disruptive, questionably helpful. You really want that slug of air to move from front to back, bottom to top, without backpressure. A side fan disrupts that flow.

 

[RandSec]

From an air-flow standpoint side-fans are totally disruptive, questionably helpful. You really want that slug of air to move from front to back, bottom to top, without backpressure. A side fan disrupts that flow.

Our first priority should be to cool the CPU, and GPU (if any), and only then the rest of the stuff on the motherboard and in slots. The classic method is to generate a howling hurricane of airflow, front to back: the faster the air moves, the more we approach having cold outside air inside a normally warm case.

We can do that more efficiently and better: We can arrange for cool outside air to DIRECTLY impact the main coolers, typically from some sort of side or back duct or port. This is better than the hurricane method can possibly be, because hurricane air must first traverse warm parts and slots and mix with warm case air before it encounters the CPU cooler.

Once the CPU has warmed the air, our best policy is to get rid of it ASAP, before it warms up everything else. That argues for a rear exhaust fan, which makes that more important than a front intake.

Since the exhaust fan must cool the MB as well as the CPU / GPU, it must move more air than goes through the main heatsinks. That argues for a negative case pressure. The modest vacuum can draw cold outside air up to the CPU cooler, which takes it from there.

 

[JAG87]

With one fan only, most definitely mount it as a rear exhaust.

 

[johnny_boy]

With one fan only, most definitely mount it as a rear exhaust.

I would but it doesn't fit!

 

[colonelciller]

do what you can.

side won't fit
back won't fit
-->front blowing in is the answer

...another part of the answer is to buy a nice quiet 92mm exhaust fan for the back
...and while you're shopping consider replacing your existing 12omm fan with a very quiet one if your current fan is noisy... even the "expensive" fans are pretty cheap

 

[Hubb1e]

I have the Fractal 1000. Mount it as a front intake. That is where it is designed to go. If you have a really hot CPU then you can get another 92mm fan but the PSU will help move air away from the CPU. I personally blocked the side vent with tape so I have a front to back airflow but that is optional and there is no GPU in my system. Fractal is going for a positive pressure design so that the air entering the case is filtered for dust. Also, that fan is not very queit so try to connect it to a fan controller that will speed up as the system heats up under load.

 

[johnny_boy]

Actually I connected the Core 1000 fan to a 3-pin CPU fan header which runs it at a lower speed than the 4-pin Chassis header and the 3-pin PSU header. It's currently spinning under 1000rpm and is barely audible.

The local computer shops I go to don't sell 92mm fans unless they're on heatsinks. I hate paying for shipping which is why I've been reluctant to buy a 92mm (here the in the Netherlands, Amazon Germany charges over 10 euros to ship a cheap 5 euro fan!) One day, one day....