How To: Properly Plan And Pick Parts For An Air-Cooled PC, Part 2

[Arbie]

RedJaron - In the spirit of this guide, I focused on the basic concepts that will fit most home installations with the least chance of going wrong. In that context, positive pressure is MUCH better. You get that by having more intake capability (filtered of course) than exhaust capability - as I said. That can be achieved either simply or elegantly; I presented a simple way.

For people to argue that with enough effort, experimentation, tuning, maintenance, and/or special circumstances the same or even better results can be achieved differently just muddies the water. Admonitions to 'keep the room clean' or 'seal up the computer' can be correct without being of any practical value to the majority of folks who would rely on this article. The common weak point of such plans - beyond the effort or complexity involved - is that they are unverifiable a priori. You won't know until you have a crapped-up motherboard or CPU cooler that you somehow didn't get it right.

==> The basics: Intake (filtered) > exhaust. Check and clean the filters after six months; if they weren't bad let them go for a year. Maybe you'll get to two-year intervals. The inside of the box will need little or no attention.

 

[RedJaron]

RedJaron - In the spirit of this guide, I focused on the basic concepts that will fit most home installations with the least chance of going wrong. In that context, positive pressure is MUCH better. You get that by having more intake capability (filtered of course) than exhaust capability - as I said. That can be achieved either simply or elegantly; I presented a simple way.

For people to argue that with enough effort, experimentation, tuning, maintenance, and/or special circumstances the same or even better results can be achieved differently just muddies the water. Admonitions to 'keep the room clean' or 'seal up the computer' can be correct without being of any practical value to the majority of folks who would rely on this article. The common weak point of such plans - beyond the effort or complexity involved - is that they are unverifiable a priori. You won't know until you have a crapped-up motherboard or CPU cooler that you somehow didn't get it right.

==> The basics: Intake (filtered) > exhaust. Check and clean the filters after six months; if they weren't bad let them go for a year. Maybe you'll get to two-year intervals. The inside of the box will need little or no attention.

If you're talking the simplest way for the general user, who won't mix and match fan speeds and sizes, then yes an extra intake is the usual solution to attain positive pressure in the case. But using blanket statements, IN ALL CAPS no less, more than suggests that you meant it as a hard universal rule, not a general guideline. At that point, you've completely lost the spirit of this guide.

And I don't understand how you can think my suggestion to keep your house clean and dust-free ( or at least as dust-free as reasonable, ) would be of no benefit to the general computer beginner ( have you seen how many people keep their systems in poorly ventilated, dirty conditions? ) Nor do I see what's inherently difficult or complex about it. And I never said housekeeping alone would keep your computer free of dust ( did I not say that I still routinely clean out the interior? ) only that it will help more than fan configuration.

Finally, I have to vehemently disagree with your maintenance cycle suggestion. Just because my car's air filter isn't dirty after three months doesn't mean it's safe to let it go six months until the next check.

 

[fb39ca4]

Why do you need a 4 pin connector for PWM? All PWM does is constantly switch on and off the power to the motor to adjust its speed.

 

[fb39ca4]

wait so ur not supposed to use arctic silver 5 on direct heat pipe heatsinks?

 

[RedJaron]

Why do you need a 4 pin connector for PWM? All PWM does is constantly switch on and off the power to the motor to adjust its speed.

The fourth cable provides the PWM timing signal and the a PWM fan has some extra circuitry to work with it. The fourth cable allows backward compatibility. You can run a PWM fan on a three-pin socket or a normal three-pin fan on a PWM socket without any damage.

wait so ur not supposed to use arctic silver 5 on direct heat pipe heatsinks?

Uh, where are you getting that? I've got AS5 between my i7 and Xigmatek Gaia ( direct heat pipe cooler, ) and I have no thermal problems.

 

[FuzzyLumpkins]

So... When can we expect the case fan shootout?

 

[zodiacfml]

got too busy. first, yeah, we all know how cooling works.
your point regarding exhaust and intakes being equal in purpose is true, only in a tube or pipe. computer cases are huge enough to be different. to understand my point, you must consider why most houses, buildings, warehouses, and similar use exhausts on high locations and never see intake fans on a window, door,floor or wall.
i tested this on a case, installing more intakes and a single exhaust. it improved HD, graphics, and chipset temps but the CPU temps were higher and to correct that would be more exhaust fans.
to make it short, i never needed extra cooling on those parts since they don't overclock (graphics not much) anyway and more fans add noise and complexity.

why seal parts that will be removed eventually? of course i meant, seal the ventilation holes since most case manufacturers have the habit making more of it to improve cooling at the expense of noise and dust control.
yes, i said fine filter on the on the intake located at the hard disk side. if it's not going to let in air, then still good since air will be sucked in from the bottom of the case.
you don't need an intake fan for good airflow, it just needs an exhaust and strategically located opening. not all vents or holes are scientifically located on cases.

[citation][nom]RedJaron[/nom]Zodiac, I can't disagree with that enough.Um, that's incorrect on multiple points. First, all air cooling is due to lower air temperatures, so I have no idea where you're trying to go with this. Second, you mention air intakes are only good at cooling HDDs, CPUs, and GPUs. Well, considering those items contribute to the vast majority of heat in a computer ( the only other thing that comes to mind it the mboard VRM, ) why is that a bad thing?But more to the point, air intakes are not only "useful to cool parts directly with ambient air." Intakes also serve an important purpose of directing airflow around in the case. Care to explain this? Heat doesn't magically stay inside the case. Fluids flow from high pressure to low pressure, regardless of positive/negative sources. If there's a vacuum, air will rush in to fill it. If there's overpressure, air will rush away to equalize. Whether you're trying to expel hot air or pull in cool air, either way will work.Intake fans don't mystically suck in dust. Dust is in the air, period. Whether it's pulled in by a fan or pulled in by the vacuum in your case, dust will enter.Right, so the next time you need to replace or upgrade a part, you have to clear off all the tape and sealant? Worst idea I've heard all month. And didn't you just say that fine filters wouldn't let the case breathe properly?Wait, didn't you just recommend sealing all holes, vents, and seams except on the front of the case?If you've sealed up the entire case, are using all fans as exhaust, and you're still lacking air pressure, that means you have poor air flow through the case, meaning poor cooling.Cases are designed with vents in certain locations for very good reasons and suddenly sealing them up is not a good idea for a healthy and cool computer system. I'll say it again. If you're concerned about dust in your computer system, proper housecleaning has a much larger impact than fan configuration.[/citation]

 

[tomhuang03]

Very helpful article! Thank you for this!

 

[halfblazed]

An easy way to determine whether machine is producing positive or negative pressure is to take a regular piece of printer paper and place it over 5.25in drive bays. If the paper sticks you have a negative airflow and if it doesn't stick, positive.

Another easy way to figure out your case's pressure is to add up the CFM on your intake fans and subtract that from the combined CFM of your exhaust.

Hope someone out there finds this helpful.

 

[Kartexa]

One problem I have with the positive air pressure on page 5 is that most people with positive air pressure use two fans in the front and one fan in the back or top, not one fan at the to and bottom, because hot air rises and a top intake would be pushing in hot air.

 

[anjaykm]

Really good article, bit of an overkill but worth it for any hardware enthusiast