Correct, a variable heat load can simulate a CPU to some extent and can be tuned to a specific heat load. That would be great if the IHS on all CPU's were flat. Most current CPU's have a concave IHS and CPU coolers are now designed to compensate for this so the base of the cooler best fits the IHS . A variable that you will have using just a heat load. In the past it was a great idea when all heat sinks were flat, but not so right now.
99% of people do not use an open bench for their systems and testing with a variable heat load does not bring all variables into play.The key is to have your airflow through the test chassis high enough that the ambient temperature inside the chassis is a close to the external ambient as possible. The variables you list are the main reasons for testing in a chassis. Sure a cooler might be the best cooling, quietest thing on an external bench, but that changes when slapped in the chassis because of the variables you noted. All of a sudden it is a noisy beast that cools fairly well and does not garner the same praise. Like I said earlier based on how it performs in our test setup will vary from the results you see on an open bench. One perspective vs. another. Open bench is nice but in a chassis is as real world as it gets regardless of the system used. If you look at the test system we use for testing coolers many of the concerns you listed are taken into account with a reference cooled card and an SSD.
Thanks for your opinion!
What is happening is testing is of a system as a complete unit. That is testing the cooler in a way very few of the readers use it.. because more than 99% of their systems are different from test system. .
Using variable heat load instead of CPU is really a non-issue. Contour can easily be the same on both. Heatsinks have not been flat for many years. My Ultra 120A (2007) is almost flat but Cogage Arrow (2009) in convex.
The variables I listed are not the issue.. except for the cooler intake air temperature that varies so much from room temperature.
A cooler that is the "quietest thing" does not become "a noisy beast" when put in a case.
Having airflow through chassis is all fine and good, as is ambient chassis temperature readings. But neither of them will consistently be the same as cooler intake air temperature. So why not monitor and use the cooler intake temperature as the base?
"in a chassis is as real world"
The "real world" is only the system being tested... at most it could include systems with identical components and cable management. Change any components or cable management in airflow and results will most likely change.
Being in a case or not.. Using a CPU or other heat source.. These are not the problem I'm trying to address. Using room ambient as base temperature instead of cooling intake air temperature is the real problem.. and one that is very easy solved.
Room ambient temperature is topically 20-22c.
Cooler intake air temperature can easily be 20-40c.. resulting in radical differences is CPU temps and therefore test results are very inaccurate. To me CPU delta temps that are up to 18c different than delta is based on temperature of air going into cooler is a variable we can easily resolved by installing a temperature sensor a few cm in front of cooler air intake and using that temperature for cooling baseline instead of room ambient.
By all mean, keep a record of room ambient too. To show how much the a cooler intake air temperature varies from room temperature.
Using the cooler intake air temperature removes most variables from resutls.
Please understand, I'm trying to discuss this problem, not argue.
Edited by doyll, 17 May 2014 - 06:47 AM.