To test a heat sink and fan assembly to the limit, a computer is not the best option. With some of the many variables, which can be attributed to the computer alone and completely outside the control of the tester, software and hardware results can be skewed to the point of being outright wrong. Things that can be controlled are often ignored and sometimes forgotten.
Factors contributing to unreliable test results that can be controlled by the tester:
Eliminating the biggest contributor to inaccurate results (the computer):
The computer needs to be eliminated from the equation if a heat sink is to be tested accurately.
Building an external test unit is the only way to eliminate the factors that are beyond the tester’s control.
A thermocouple can be used if you wish to test specific points on the HSF for variance, which can indicate a poor performing or bad/damaged HSF.
Using water as a heat transfer medium allows for more control of environmental factors that are otherwise left unchecked.
Using water will allow for repeatability in testing. This allows the temperatures to be easily stabilized and the maximum temperature will usually be in a predictable range; thus allowing for data sets to be formulated. After a point, head to head tests will no longer be necessary.
Testing temperature scaling and humidity is a necessity as they will work together to give a more controlled testing environment.
Though the temperatures should remain uniform, there is no guarantee. ALWAYS CHECK TEMPERATURES AT MORE THAN ONE POINT!
There are many other types of tests that can be done with an out of the box setup. The testing above is just a start.
Data collection: Keeping track of information allows the tester to build a database of results. By studying the variances, from run to run, choose a control heat sink to work with as a standard for comparison; a benchmark of sorts. The best way to record and store the information is with a meter that will log the information and allow output in a standard form that can be used in something like Excel or Open Office.
Obtaining a testing pan and plate: Most of these items are easy to acquire, save the box or pan. Local fabrication shops usually have plenty of scrap around and will usually sell it at a discount rate. If you are a product tester, the shop may cut you a break for a little free advertising in your review/blog, or you can part with the ~ $70 – $200 and just have it made.
That is all for now. Feel free to comment or ask questions and I will be happy to help in any way that I can.