Front case fans really necessary?

Necroz · Post by **Necroz** » Wed Jul 23, 2003 4:03 am

Are the fans in the front of the case really necessary? Right now I have two in the front two in the back one out the side and the power supply vents in the back. Basically four fans are pumping air out and two are pulling it in. Is this creating a negative pressure problem? Am I restricting my airflow with the front fans?

Thanks!

Katana Man · Post by **Katana Man** » Thu Jul 24, 2003 7:20 am

They are not necessary, but certainly preferred in order to maintain positive air pressure. Positive air pressure is important with the lastest quiet PSU's. These quiet PSU's generally do not move much air, and negative air pressure can cause the airflow to come to a halt.

For example, on the opposite extreme, if you had front fans and no rear fans, the air would exit through the PSU and it would be helping the PSU to move air. Typically, that's not always best to move ALL the air through the PSU since it may be warm air. So I've found the best results is to have 1 rear fan and the PSU as the exaust. I'll make sure that my front fans push more than the rear to maintain positive air pressure.

POLIST8 · Post by **POLIST8** » Thu Jul 24, 2003 7:55 am

I just mounted my HDDs at the bottom of the case, use a panaflo intake to blow over them, and a panaflo in the power supply to exhaust air.

It's damn quiet, and my disks (the most important items in my system) are nice and cool.

Katana Man · Post by **Katana Man** » Thu Jul 24, 2003 8:26 am

You bring up a good point. Front fans provide another advantage in cooling hard drives. They will cause the great majority of incoming cool air to flow in from one location. You can use this to cool the drives.

Necroz · Post by **Necroz** » Thu Jul 24, 2003 8:41 am

Katana Man wrote:They are not necessary, but certainly preferred in order to maintain positive air pressure. Positive air pressure is important with the lastest quiet PSU's. These quiet PSU's generally do not move much air, and negative air pressure can cause the airflow to come to a halt.

That answered my question perfectly. All of my fans are Papst. I was going to try a higher CFM fan (Panaflo or Silenx) in the rear but it sounds like I should put them up front to maintain positive pressure.

Thanks again.

Katana Man · Post by **Katana Man** » Thu Jul 24, 2003 8:45 am

Correct, put the stronger ones up front. If all fans are the same brand/model, then use a rheostat or voltage reduction on the rear fan(s). Click on my signature to see an example.

I also can't stress enough what an improvement it is to use modder's mesh on the front. It doesn't seem to sink in to people who read about it. I guess some people feel it lets the sound out, but it doesn't. I'll explain:

When you use a front mesh grill like this, it allows your computer to breath easy. Therefore ALL fans can be reduced in speed and everything will run quiet and cool. If you've never experienced a Papst 120mm running at 4.9V, then you're missing out

marc999 · Post by **marc999** » Thu Jul 24, 2003 9:53 am

Hi Katana Man,
RE:

also can't stress enough what an improvement it is to use modder's mesh on the front. It doesn't seem to sink in to people who read about it. I guess some people feel it lets the sound out, but it doesn't.

I just wanted to say that I still think it would let out noise through the front. Why wouldn't it ? I see your point about the reduced fan voltage, but that doesn't stop noise from other components from coming out. I have a D8000 with the Modder's Mesh and I like it, but it's still noisy. The noise is from my WD Raptors (even though they're in Smart Drive 2002s) and my Panaflow L1A @12V on my SLK-800. I plan on installing AcoustiPack, which may negate the above noise. If it doesn't, I plan on propping my case up on feet and cutting out a 120mm hole in the bottom (Lian-Li PC-6070 style) with C-strip and rubber grommets (Coolcases.com style). This seems to me the best of both worlds. I may end up doing it anyways just for that reason.

Katana Man · Post by **Katana Man** » Thu Jul 24, 2003 10:27 am

Looks like my D8000 setup is a bit better than yours. I also have it sitting on carpet under my desk. But I've also done the same technique to 2 other machines:

http://forums.silentpcreview.com//viewtopic.php?t=4235
http://forums.silentpcreview.com//viewtopic.php?t=4745

I don't have any noise measuring equipment, but if you stand near any of these machines, you can't hear them at all. If you sit in a chair, and you turn the lights off, you might be able to hear it a little. Putting your head under the desk will let you hear that it's running.

But I don't want to get too far off topic. My point is, in my experience, front fans will aid in positive air pressure. Easy breathing up front will also help things as well.

POLIST8 · Post by **POLIST8** » Thu Jul 24, 2003 12:53 pm

I keep them in the original 3.5" tray and disconnected it from the chassis.

I then velcroed the bottom of the 3.5" tray with the drives in it and put it on the bottom of my case (which is dampened). There is no sound from my disks while idle, only a little when seeking.

Much cooler too!

POLIST8 · Post by **POLIST8** » Thu Jul 24, 2003 1:04 pm

2 HDDs

1 120GB 7200.7
1 120GB ATA V

I still like the support the 3.5" tray offers, as well as the slight heatsinking and heat distribution it offers.

josephclemente · Post by **josephclemente** » Thu Jul 24, 2003 1:20 pm

Necroz wrote:Are the fans in the front of the case really necessary? Right now I have two in the front two in the back one out the side and the power supply vents in the back. Basically four fans are pumping air out and two are pulling it in. Is this creating a negative pressure problem? Am I restricting my airflow with the front fans?

Thanks!

Only if you consider "negative pressure" to be a problem. With good case design and vents in the right locations, I have plenty of airflow in the lower-front of my machine to cool hard drives. But there are NO fans on the front of the computer. I have blocked some useless vents on the rear of my case to ensure this effect occurs.

As for sucking dust through drives, I don't buy it. 1 - I don't use floppies anymore. 2 - my optical drives seal nicely when closed.

aphonos · Post by **aphonos** » Thu Jul 24, 2003 6:55 pm

Katana Man wrote:I also can't stress enough what an improvement it is to use modder's mesh on the front. It doesn't seem to sink in to people who read about it. I guess some people feel it lets the sound out, but it doesn't. I'll explain:

When you use a front mesh grill like this, it allows your computer to breath easy. Therefore ALL fans can be reduced in speed and everything will run quiet and cool. If you've never experienced a Papst 120mm running at 4.9V, then you're missing out

Counter point: there are noises that can come through the modders mesh besides fan noise (ie HDD seek/whine). And if you can get your fans running quietly without having to open up the front of the case (ie through other airflow paths), then you've come out ahead.

YMMV. I have read Katana Man's posts and seen the setup of his machine in the gallery and the fact that he seems so very satisfied with the modders mesh setup has given me pause on my thinking about front case openings.

Wedge · Post by **Wedge** » Fri Jul 25, 2003 6:21 pm

Necroz wrote:Are the fans in the front of the case really necessary?

I'm not sure if they are necessary, probably depends on how many drives you have and how hot the case is in general terms?

Case in point: I have a Gateway computer that shipped without a front fan and a single 40GB drive. Obviously Gateway feels that there is sufficient airflow because they promise to cover my parts for 3 years (i.e., they don't expect the drive to fail due to heat within 3 years). So far, so good. 2 years later I have added an 80GB drive and I felt it best to go ahead and add an intake fan (L1A).

Additionally, this computer didn't ship with an exhaust fan either

I don't know if it was deemed unnecessary or if it was carelessness during the build of this PC. If I had to guess, I think Gateway felt it would stay alive at least three years without incident. Of course, I slapped an L1A in the back as well, just to be sure air is flowing.

Also, a word on negaitive pressure.....it seems to me that if you seal up any extraneous openings in the back and front, air would naturally create a healthy flow from the front when a fan is placed in the rear for exhaust. Where else can the air come from if you seal off all holes except the holes where you want it to come from? I hope that makes sense.

Katana Man · Post by **Katana Man** » Fri Jul 25, 2003 6:45 pm

Wedge wrote: Also, a word on negaitive pressure.....it seems to me that if you seal up any extraneous openings in the back and front, air would naturally create a healthy flow from the front when a fan is placed in the rear for exhaust. Where else can the air come from if you seal off all holes except the holes where you want it to come from? I hope that makes sense.

Yes, you can certainly control where the air flows in, but it's still negative pressure if all of your fans are in the rear and blowing out (exaust). The amount of negative pressure depends directly on how much air is allowed in with little resistance. An extreme example: if the front of your case is completely torn off (a gaping hole), you would not have a problem with negative pressure.

Wedge · Post by **Wedge** » Sat Jul 26, 2003 2:24 pm

So negative pressure is to be avoided as much as possible?

Katana Man · Post by **Katana Man** » Sun Jul 27, 2003 8:10 pm

A computer will run just fine with negative pressure. It's not a very big deal at all. But optimally, positive pressure controls the dust better, cools hard drives better, and helps quiet PSU's instead of fighting them.

Will_Corrigan · Post by **Will_Corrigan** » Sun Jul 27, 2003 11:55 pm

Negative pressure is oftentimes a consequence of silent computing as even a slowish intake fan is likely to be audible. Personally, I just use a 5-volted Panaflo to make sure the HDs stay cool and provide a small push for air entering the case.

Front case fans really necessary?

Front case fans really necessary?

Re: Front case fans really necessary?

Re: Front case fans really necessary?

Re: Front case fans really necessary?