A case with top vents?

crispyfish · Post by **crispyfish** » Tue Mar 06, 2007 10:26 pm

If you look at nearly any home theater component, you'll see that it has numerous vents on top to allow heat to rise out. Why don't PC manufacturers do the same? Wouldn't it greatly increase passive cooling abilities? Or is dust too much of a problem?

crispyfish · Post by **crispyfish** » Wed Mar 07, 2007 2:37 pm

Hmmm... I just discovered that some of the nmediapc cases have top vents. Interesting...

pyogenes · Post by **pyogenes** » Wed Mar 07, 2007 8:21 pm

vents work if there's very little airflow and convection currents are the strongest source of airflow. In a well designed PC, airflow is strong enough to push the hot air out of the system before it can reach a vent.

Worse yet, vents can reduce air flow efficiency if they let air into the system and out the exhaust without cooling any components (effectively reducing the amount of heated air leaving the system).

Bluefront · Post by **Bluefront** » Thu Mar 08, 2007 2:57 am

pyogenes.....you make it sound so simple. It's not. Vents on the top of a computer are an obvious place for hot air to leave a computer case, and the airflow can do so unassisted by a fan. The problem with this is the location of normal components. The PSU runs hot, so the most effective place for it is on the top, so the heat can go straight up and out, without heating up any other components. Then there's the optical drive.....the most effective place for it is on the top of the case, making it easy to access. Put those two items on the top of a computer case, and there is little space left on the top for any effective case venting. Put the PSU on the bottom means you need a fan to cool the PSU. My solution to this.....mount a fanless PSU partially outside the case, and mount the optical drive in the second bay down. This gives you the ability to passively vent the top.....and use minimal fan-assisted airflow. Like this.....no exhaust fans, all the air goes out the top.

Oh....dust you say? There is no dust problem here. The intakes are filtered, and the top vents are indirect, so dust cannot just fall in. the top is easily cleaned with an occasional vacuum.

Shaman · Post by **Shaman** » Thu Mar 08, 2007 4:22 am

Convection cooling works better in htpc cases because they're usually desktop cases (horizontal). So the heat from the cpu/northbridge/graphics card goes straight up and out of those top vents without interfering with eachother much. In normal tower cases (assuming that's what you mean by 'PC manufacturers') this method wouldn't be as effective because the heat from the graphics card would heat the northbridge up, and these two would then heat the cpu heatsink even more. These three heat sources would then heat the PSU up etc well to have enough vents at the top, the PSU would have to be mounted at the bottom of the case, so you have to start the heating cycle described above starting from the PSU.

ronrem · Post by **ronrem** » Thu Mar 08, 2007 5:16 am

I'd like to try some wooden louvers as vents...look great stained red oak with gloss Man-O-War,deflect air and sound well without adding resistance.

Bluefront's right on about a fanless PSU,you either have a top mount or a seperate and well vented chamber-or it heats the internal space so you need an extra case fan.

pyogenes · Post by **pyogenes** » Thu Mar 08, 2007 9:01 am

Bluefront wrote:pyogenes.....you make it sound so simple. It's not.

I was limiting my response to why manufacturers design cases as they do, not whether vents are useful in all situations. Unless we're talking about fanless cases or custom jobs, it's reasonable to assume usage of fans for air flow since manufacturers design products based on the needs of the majority, not extremists.

Under that assumption, my pithy comments are realistic.

BTW, nice case design. How long did it take to build?

crispyfish · Post by **crispyfish** » Thu Mar 08, 2007 9:27 am

Sorry, I should have been more clear. I think this would make the most sense in a desktop HTPC configuration. Obviously a tower setup would have different considerations due to heat rising and crossing over other components.