This article will introduce you to some concepts in System Design such as environmental specifications. To be even more specific, thermal specifications. I will show you how to test your laptop for thermal bugs before your laptop fails when you need it the most. Although these tests may not uncover all design defects, the tests should flush out gross design and manufacturing errors. Armed with this knowledge allows you to return your laptop for a refund and buy a different model or at the very least be able to argue with tech support.

There are two main challenges that electrical and mechanical engineers face when designing a laptop; 1) Heat and; 2) Real Estate. Real estate is the term used to describe the amount of area available to the electrical and mechanical engineers. The electrical engineers have to worry about cramming all the features requested by marketing onto a PCB. The mechanical engineers have to fret over sticking the PCB and other peripherals into the laptop chassis or skin while paying close attention to the thermal characteristics. Heat (thermal) is the number one enemy of any laptop. Even servers and desktops have to deal with heat. When a large system such as a server or desktop has thermal problems, the solution is usually to adjust airflow with fans or to add more holes in the chassis. With laptops one cannot just add a fan or drill holes, simply because there is no place to add a fan, unless the CD-DRIVE is not needed. Traditionally the CPU has been the hottest component in laptops and receives the most attention. This probably still holds true even today. Although I haven't looked at any mobile CPU specifications lately. In modern laptop design even the software engineer (BIOS Engineer) has to pay attention to thermal issues. The BIOS engineer must read thermal sensors and adjust CPU speeds or simply shut down the system at critical temperatures or turn off unused peripherals such as hard drives. As stated above, a laptop can have multiple points of thermal failure.

In the design phase, the laptops are usually put through environmental or reliability testing to stress these design areas and then some sort of corrective action is taken with failures.

Environmental Chamber, courtesy of TestEquity

Environmental chambers are usually used for testing. An environmental chamber looks like a huge oven. The chamber can be programmed to cycle through temperature and humidity. Usually the laptop is running an OS with some sort of stress test while these environmental variables are cycled through (hot and cold temps). However, once a laptop goes to manufacturing it will never see these rigorous testing methodologies again. Manufacturing defects can occur such as improperly assembled CPU/heat sinks. Defects like not enough thermal adhesive on a video controller heat sink, a hard drive than runs hotter than spec'd. A memory DIMM that degrades with heat worse than rated can cause all sorts of weird problems.

Gee, how does average Joe test his laptop without having a million dollar lab and an army of engineers? You probably already have the three pieces of key test equipment in your home; carpet, an oven, and a refrigerator. Carpet? Yeah, you will use the carpet as a soft landing as to not scratch or dent you laptop when you drop it from a height of three feet multiple times at different angles while closed. The drop test (the shock in shock and vibration) should jar any improperly assembled components and loosen them. After the drop test, place the laptop in an oven under electrical power running a stress test. Don't close the door all the way, leave a crack at the top and run the power cord through it. The heat being dissipated from the laptop will be enough to raise the ambient temperature (temperature inside the oven) for this test. I would run this stress test for twenty-four hours. After the oven, place the laptop in a running refrigerator under battery power for two hours. Place the laptop on a shelf all by itself. Also place sugar cubes on the same shelf to absorb any excess humidity. You could probably run the cold test longer, but you would have to closely monitor condensation (water). Next place the laptop on a table under electrical power and run the stress test for forty-eight hours. After each test, power off the laptop then power back on. Any lock-ups, boot failures or any other weirdness suggests that you have a thermal problem and probably a defective laptop.

For the stress test you can run a good diagnostics program that can concurrently execute tests on the CD-ROM drive, hard drive, and video subsystem. Passmark software [1] offers a good diagnostics program called BurnInTest [2]. It runs under Linux and Windows. Passmark also offers a free thirty day evaluation. For maximum stress, you could turn off video testing under BurnInTest and run SPECviewperf® 8.1 [3] concurrently with BurnInTest. You would have to loop SPECviewperf though. Even if you forgo the oven and refrigerator tests, running the stress test for forty-eight hours may even reveal some issues.

Disclaimer: Execute the above tests at your own risk.