Computer Case Cooling: Design Principles

Design Principles for
Computer Case Cooling

(If you jumped straight to this page from another site, please start at the CCC title page.)
There are 4 temperatures of interest for CCC.

First is the room air temperature (called ambient temp) at the inlet to the case.

The next is the surface temps of the electronics in the case.

There is the average temperature of the air inside the case.

And lastly, the case exhaust temp.

If you want a cool running computer, your main objective is to lower all 4 temperatures. Unfortunately, the most important temperature (electronics) is the hardest to measure. Fortunately, you can infer the electronics surface temperature by measuring the case exhaust temperature. There is not a direct conversion factor, but using the case exhaust temp and compensating for a baseline ambient temp will allow you to correlate modifications to relative changes in electronics temp.

There is example temperature test data on the Fast, Cheap, and Easy results page.

I have a 4 gig Seagate SCSI Barracuda (7200 RPM) and boy can that thing really put out the BTU's! Seagate's site has some interesting thermal cooling ideas and I give them high marks for it. While reading about their new 10,000 RPM Cheetah drive I came across some advice to alleviate concerns about the excesive heat outpout from such an energy hog. They said to make sure the unit is screwed into the metal computer case because there is significant conductive heat transfer through it. I immediately put in 2 missing support screws on my Barracuda because I don't want to have to buy another $800 drive (yet). The next 2 figures are from the Seagate Barracuda manual. In conclusion, remember that high performance hard drives require special thermal attention.

Satifactory case flow (FCE method)

Best Case flow

A good, open plastic grille (metal in front of plastic). Note there is no air filter.

Same tower case, using light to check openings.

Generic mini case using an "air tunnel" mod. More about this enhancement soon.

Testing
I am an advocate of testing. There are not many equations at this site as you can see. The equations are readily available in all Heat Transfer and Thermodynamics textbooks. I firmly believe that testing before, during, and after design mods on actual or similar hardware is the most significant method for thermal design solutions. Go get some thermometers or thermocouples and make some measurements. Go get some thermometers or thermocouples and make some measurements. Do a test and get some data. It really is worth the effort.

Further Information

Heat transfer is most often used by Mechanical Engineers and Desginers. In difficult situations, Mechanical Engineers will investigated convection heat transmission by using theoretical, numerical, and empirical methods of analysis. There is example temperature test data on the Fast, Cheap, and Easy results page.

To find more information on the subject of Heat Transfer, use a search engine with keys words such as; heat transfer convection design thermal cooling hardware temperature

To weed out the course descriptions, you may need to add: not university not class

Here are some resources

Overheating Problems

comp.sys.ibm.pc.hardware.chips A newsgroup.

Thermocouples and Thermocouple Assemblies / Introduction to Thermocouples A site by the supplier of instrumenation. Includes other good articles as well. I have used their catalogs for years.

I hope this site is useful to you. I plan to post a heat-loads page someday. I would like to have estimates of thermal output (in wattage) for periphials such as hard drives and motherboards (CPUs are about 15w max.). If you know of such info, please email me.
Click here to go to the overclocking page.

DISCLAIMER: I'm not responsible for anything that can happen to your computer system!!! I'm NOT RESPONSIBLE for errors you make from suggestions on this site. I'm not responsible for mistakes on this site. Although these concepts worked for me, your mileage may vary. YOU should be extremely careful around an open computer case, both for your own personal safety and to avoid breaking the computer. Do not attempt modifications unless you are comfortable with them, understand the principles behind them, and are trained.

You are welcome to link to this site, but please don't copy it.

| CCC |
| FCE | Concepts | Principles | OC |

	(If you jumped straight to this page from another site, please start at the CCC title page.) There are 4 temperatures of interest for CCC. First is the room air temperature (called ambient temp) at the inlet to the case. The next is the surface temps of the electronics in the case. There is the average temperature of the air inside the case. And lastly, the case exhaust temp. If you want a cool running computer, your main objective is to lower all 4 temperatures. Unfortunately, the most important temperature (electronics) is the hardest to measure. Fortunately, you can infer the electronics surface temperature by measuring the case exhaust temperature. There is not a direct conversion factor, but using the case exhaust temp and compensating for a baseline ambient temp will allow you to correlate modifications to relative changes in electronics temp. There is example temperature test data on the Fast, Cheap, and Easy results page.
	I have a 4 gig Seagate SCSI Barracuda (7200 RPM) and boy can that thing really put out the BTU's! Seagate's site has some interesting thermal cooling ideas and I give them high marks for it. While reading about their new 10,000 RPM Cheetah drive I came across some advice to alleviate concerns about the excesive heat outpout from such an energy hog. They said to make sure the unit is screwed into the metal computer case because there is significant conductive heat transfer through it. I immediately put in 2 missing support screws on my Barracuda because I don't want to have to buy another $800 drive (yet). The next 2 figures are from the Seagate Barracuda manual. In conclusion, remember that high performance hard drives require special thermal attention. Satifactory case flow (FCE method) Best Case flow A good, open plastic grille (metal in front of plastic). Note there is no air filter. Same tower case, using light to check openings. Generic mini case using an "air tunnel" mod. More about this enhancement soon.
	Testing I am an advocate of testing. There are not many equations at this site as you can see. The equations are readily available in all Heat Transfer and Thermodynamics textbooks. I firmly believe that testing before, during, and after design mods on actual or similar hardware is the most significant method for thermal design solutions. Go get some thermometers or thermocouples and make some measurements. Go get some thermometers or thermocouples and make some measurements. Do a test and get some data. It really is worth the effort. Further Information Heat transfer is most often used by Mechanical Engineers and Desginers. In difficult situations, Mechanical Engineers will investigated convection heat transmission by using theoretical, numerical, and empirical methods of analysis. There is example temperature test data on the Fast, Cheap, and Easy results page. To find more information on the subject of Heat Transfer, use a search engine with keys words such as; `heat transfer convection design thermal cooling hardware temperature` To weed out the course descriptions, you may need to add: `not university not class` Here are some resources Overheating Problems comp.sys.ibm.pc.hardware.chips A newsgroup. Thermocouples and Thermocouple Assemblies / Introduction to Thermocouples A site by the supplier of instrumenation. Includes other good articles as well. I have used their catalogs for years.
	I hope this site is useful to you. I plan to post a heat-loads page someday. I would like to have estimates of thermal output (in wattage) for periphials such as hard drives and motherboards (CPUs are about 15w max.). If you know of such info, please email me. Click here to go to the overclocking page.