Cooling A Cabinet-Mounted PC

Hi Fred, I was wondering what your opinion is on the use of hideaway computer cabinets with regards to air flow/circulation for the computer caseand monitor?  To avoid confusion about the type of cabinet I am referring to (I googled computer cabinets and many pages seemed to refer to something sounding more like a case housing) an example can be found here
http://www.cheapaschips.com.au/prodinfo3.asp?productcode=FA1220

I didn’t find much in the way of information on google.  Only that if you left the computer on all day with the doors shut it would die an early death which I thought was obvious.  I am wanting to know how it would go running with the doors open and only being switched on when in use.

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If you think my question could be useful to others, please feel free to include it in the LangaList.  Your LangaList is my favourite email and I always learn cool stuff from reading it. Thanks, Mady

There are many variables, but two main issues rise to the fore:

"Passively" cooled components (fanless devices, such as monitors) need more open space around them than do "actively" cooled components (such as PCs with fans) because passive cooling depends on the relatively gentle forces of convection to move heat out of a device. Passively-cooled, fanless devices generally need to move a lot of air at extremely low speeds— that’s why the backs of most monitor cases have so many openings, louvers, and grills, for example. Owner’s manuals often will specify how much space a passively-cooled device requires for adequate airflow: often, it’s two- or three finger-widths to the sides, and about a hand’s width above a passively-cooled electronic device; with more space being better than less.

A fan-cooled device can do OK in a smaller space as it powers the air it needs for cooling into, though, and out of the case— the gentle forces of natural convection play little or no part. But a fan-cooled device (like a standard PC) still needs at least a modest amount of airspace. For one thing, the expelled warm air has to go somewhere; if the PC’s fans are blowing into what is essentially a closed space, very little air will actually move, and the PC may overheat. Or,  if a PC is in too-snug a space, warm air may be drawn back into the case in a kind of recirculating closed loop, with overheating the likely eventual result.

But note that an open or partially-open back on a cabinet can help solve the above problems, as long as the cabinet isn’t snug against a wall. An open-backed cabinet (or one where you cut ventilation holes where they won’t be seen, behind the components you’re installing) that stands two or three finger-widths away from the wall will probably be fine, especially if the devices are only used when the cabinet doors are open.

The above addresses getting rid of heat, but the other main issue is limiting heat gain in the first place. For example, LCD monitors produce only a fraction of the heat of a standard CRT monitor, and thus have lower ventilation requirements. Laptops and PCs with low-power motherboards (such as some "whitebox" PCs we’ve discussed in the past: http://www.informationweek.com/story/IWK20030206S0014 ) need much less cooling than some top-of-the-line, full-blown desktop PCs. And, due to the way the chips are manufactured, Intel chips generally run cooler than AMD chips of similar clockspeed and power. (Normally, the difference doesn’t matter much, but in heat-critical situations, it might….)

So, by providing a reasonable amount of airflow, and/or carefully selecting lower-power devices, "hideaway" cases and cabinets can work fine!

Fred Langa

About Fred Langa

Fred Langa is senior editor. His LangaList Newsletter merged with Windows Secrets on Nov. 16, 2006. Prior to that, Fred was editor of Byte Magazine (1987 to 1991) and editorial director of CMP Media (1991 to 1996), overseeing Windows Magazine and others.