PC Basic Case Air Circulation.

[fastredpacman]

I saw this article on pc cooling and thought Id get your opinions on it. Here is the article: http://www.techtastic.ca/articles/aircase.html  

Is that diagram acurate? Just wanna know because Im building this monster computer with all the roms from almost every emulator and I wanna make sure its cool.

[krick]

Yep.  The general idea is bring in cool air at the bottom with an intake fan and exhaust hot air at the top of the case using the power supply fan and possibly an additional exhaust fan.  I think the top mounted "blowhole" fan is overkill in most situations.

There are interesting variations.  One idea is to use a ducting tube to bring cool air from the outside and deposit it directly onto the CPU heatsink fan with the fan oriented to blow downward on the heatsink.

But in general, if you have a good intake fan at the bottom and exhaust fan (i.e. power supply fan) at the top, you should be good as far as case flow goes.

[cdbrown]

Alot of cases also have an intake on the side panel to blow fresh air over the sound and graphics card and just provide another source of air

[patrickl]

Alot of cases also have an intake on the side panel to blow fresh air over the sound and graphics card and just provide another source of air

I just got a new PC with a hole in the side as well. There is a duct on the CPU that blows the heat from the CPU fan straight out the side.

[daywane]

My newest Pc I have just built has exhaust fan on the clear side , also exhaust from the power supply,
intake from bttm front. I have never seen exhaust on the top. not saying there not out there, I just have never run into one yet.

[Crazy Cooter]

What setup do you have for the computer?  You may not need a fan system that "robust".  I've built several computers and only had issues with a Duron 600 (@1Ghz) and a T-bird 700 (@950Mhz) where something "drastic" was needed for heat control.  All others that I have built have run relatively cool and only used simple fan systems.  FWIW, The duron actually made it up to almost 1.2Ghz with a water cooled setup, but now is used as a 850Mhz mp3 player with only 2 fans (one on processor and the one on the power supply.

[patrickl]

The cooling issues described here aren't overly "robust". If you want robust cooling ... a while back I bought a HP LH3000 NetServer.  This thing has so many fans (IIRC 6 x 12cm and 1x9cm) that I (almost) needed to put blocks in front of the wheels to keep the thing from moving! But at least the temperature inside the case rarely goes more than one or two degrees above room temperature.

[Crazy Cooter]

My cousin had a case that was like that.  It had like 5 fans normally and then at LAN parties he used a house fan with the side removed.  VERY poor case design IMO.  I disagree with that linked article though.  They say that that layout is a minimum and that you should have more airflow out of the case than in.  

1- "will give you the ideal minimum fan setup"
2- "All though this is sufficient for un-overclocked computers, it won't do for one that is overclocked."
3- "Use equal or more cfm's(cubic feet per minute) of fans exhausting out, than air going in"

1- I believe the minimum airflow (CFM) can be achieved with a 120mm fan intake in the lower front and the power supply fan exhausting out the top rear for most cases.  A good way to keep an eye on things is with a program called "motherboard monitor".  It will run in the background and can display the temp inside the case and the cpu for motherboards that support it.
2- See above and reference my previous post.
3- I do the opposite and here's why:  If your exhaust cfm exceeds the intake, your case becomes a vaccuum.  It will draw in air through other areas like your cd drive.  If your intake cfm exceeds the exhaust, you create a positive pressure within the case and you push air out through gaps like your cd drive.  Assuming you use a filter material on the intake fan, you can push cleaner (less dust) air out, rather than pulling dirtier (more dust) in.

That's how I've always approached air cooled setups.

TIPS
--------
*Larger fans typically move more CFM with less noise.
*Monitor your temps under full load (SiSoft Sandra or 3d games are a good test bed)
*Intake CFM > Exhaust CFM
*Filter the intake air & Clean the case occassionally.

[GGKoul]

If your overclocking.. then the more fans the better...

If your not, the standard, 1 front intake & 2 rear should be fine.

[patrickl]

...
3- I do the opposite and here's why:  If your exhaust cfm exceeds the intake, your case becomes a vaccuum.  It will draw in air through other areas like your cd drive.  If your intake cfm exceeds the exhaust, you create a positive pressure within the case and you push air out through gaps like your cd drive.  Assuming you use a filter material on the intake fan, you can push cleaner (less dust) air out, rather than pulling dirtier (more dust) in.

Yeah that's a very good remark. The HP NetServer I was talking about basically acts like a windtunnel. It has 4 of 12cm fans in the middle sucking air through the front and expelling it backwards. This way it sux the air through the machine (over the hard disks and out through the power supply). This design does work real well in keeping everything really cool. Especially the hard disks (5 high speed scsi disks) run remarkably cool.

No wthe point is: I know I'm supposed to keep these meachines in a clean environment, but the CD unit and such get covered with dust.

On the other hand won't the dust just go in another way and settle on the inside of the case? (I agree that's better than it being inside the CD player of course)

I also have a few rack mounted servers and these have one (or two) 12cm fan(s) at the front with dust filters behind them. Another option would probably be to vacuum the room once a year (or more even)  

I think the best design is the one with only a single fan though. As krick described. I have some desktop computers like that. (The power supply fan air intake is ducted over the CPU)  The're silent (only one fan) and still run pretty cool. The're just 1Ghz though (dunno how such a design would translate to a 3+Ghz CPU with faster harddisk and heat producing videocards). Modern computers need better cooling than older computers do. I'd say it's pretty hard to give a general design that works in any situation.

[fastredpacman]

The only reason I was concerned was because of the 5 hard drives in the case. And the room inside the cab will get pretty hot. So along with the cab inside the case I was planning on putting extra fans. What do you guys think?

[Crazy Cooter]

5 drives?  RAID 0+1 with a storage drive?

Anyhow, if this is all going in a cabinet, why use a case at all?  Use the cpu fan and put a vent fan on the cabinet.  Monitor your temps and add cabinet fans if the they get out of hand.

[Xiaou2]

 Ive had 3 hard drives fail so far - before I finally realized the main reason... Heat!

  Most older or smaller pc cases have drive bays that stack the hd's within a few millimeters appart.  The problem is that the heat from the bottom drive will make the top drive twice as hot.  Of course - the more drives you have the hotter your system will get.

 Heat causes the metal to expand - and with hd's - that is a big problem.  It eventaully causes the heads to become missaligned and damaged due to friction.

 I HIGHLY Sugggest that you get a large server style case.  The new cases have 2 removable drive bays (3 drives in each possible)... and fans that sit right in front of them : )  
 
 One of the spots is for the floppy - but I got a 5.14" adapter so that the floppy sits in a cd bay (with extra usb ports too : ).   This allows me to space the drives appart by one inch... which allows the fans to blow more effectively across the drive surfaces.

 Ive got an older processor - that dosnt get that hot... but for anything over a gig... I recomend cutting a hole in the sidepanel and popping a fan in there.

 Ive found... that by trying to draw air out of the case by the cpu hardly reduced the tempature.  But by pushing air right twords the cpu - it cooled it considerably.  This is true for the hd fans, and anything else for that matter.  Yes... it will suck more dust into the system... but hey, you can remove that every few months as needed.

  I run 4 drives in my system:

 1) os
 2) os backup
 3) main data drive
 4) Main data backup drive

 I do not use automatic raid.  I backup my data manually using norton ghost - about every month.   And if I need to back up something sooner... I just place a duplicate on the backup drive manually untill I can do a full drive copy.   Reason?    

 If a virus hits... it will not destoy all my drives.  (well, less likly... but better if u unplug drives untill needed) If my OS gets quirkey or unbootable... I can just switch to the backup knowing it will work... and re-ghost.

This setup has been a lifesaver a few times already (many os swaps, one unfixable sector problem)

 One other thing worth mentioning... is power.  If you run 5 drives at once, as well as cd roms, many fans, and more... you should invest in an expensive powerfull power supply.  Else... your supply will start to have trouble keeping up... will have trouble booting your drives correctly, and may cause cpu and or drive damages over time.

 If things get ultra hot (summer),  and you do not have AC,  then either do not run your pc... or take off the sidepanel and place a huge boxfan in front of it.  (this is what I do)  

 

[NoOne=NBA=]

I've got an Enermax case that uses the setup shown in the original post, with two exceptions.
It has a side fan in the windowed area for intake, and has TWO exhaust fan holes below the power supply.

I've got all the fan holes populated, except the one immediately below the power supply, and haven't had any problems at all.
I'm running an Athlon 2000+ that is NOT overclocked, so I'm not really taxing the cooling system at all.

My general take on fans though is "the more fans the better".
I've never heard of a computer having problems from running too COOL.
As long as it doesn't make too much noise, I'd fill them all, and add a side one for good measure.

[patrickl]

 Ive had 3 hard drives fail so far - before I finally realized the main reason... Heat!

  Most older or smaller pc cases have drive bays that stack the hd's within a few millimeters appart.  The problem is that the heat from the bottom drive will make the top drive twice as hot.  Of course - the more drives you have the hotter your system will get.

I learnt the same lesson the same hard way. I don't know why (desktop) case builders seem to forget to cool the disks, but it's probably the most annoying part to die on you. And indeed, the more disks the bigger the problem.

Ive found... that by trying to draw air out of the case by the cpu hardly reduced the tempature.  But by pushing air right twords the cpu - it cooled it considerably.  

Oops, I said I had an exhaust hole over my CPU, but it's actually an air intake ...  

[captainpotato]

If your overclocking.. then the more fans the better...

If your not, the standard, 1 front intake & 2 rear should be fine.

It depends on the case design - my K6-2 500 box had really badly designed air inlets/outlets (hardly any of them), and on a hot Australian summer's day, it could lock up within 15 seconds of being turned on. On days like this, it meant blowing a 30cm cooling fan into the decased chassis (which meant the operator overheated instead...)

Since I modded the case to help with this, it's a lot better. IMO, although a fan or two should be enough, if the case doesn't have enough inlets and outlets for airflow, then fans are a complete waste of time.

[fastredpacman]

Wow who knew that there was so much invloved in just cooling the pc.