…and around and around we go…
MacTron, I have the utmost respect for you but I think you are missing my point.
Although you are probably correct that the "thin" plates are zinc, They are not soldered but rather "welded" to the base plate by some sort of (MIG?) process that is not affected by whatever temps the base plate reaches and they stay put. Notice how each one is bent 90° to maximize the contact area. The heat isn't flowing through a solder paste or such.
BUT
I am not debating only the absolute thermal performance of the 3 types. I really don't think that any of us here on the Forum are equipped with sophisticated equipment to accurately compare their real-world thermal performance. This also requires some elaborate advanced math (I am not ashamed to admit is way beyond me) just to compare say, the radiating efficiency of the 24 thick fins on the one versus the 39 thin ones on the other. However, since all but the two outer ones on each radiate into the narrow spaces between themselves and their neighbors, the actual airflow in those spaces, both its incoming temperature and its velocity become a huge factor. Therefore, changing the stock fan out for any other unit will affect performance regardless of the fan noise - for example, two virtually identical fans with identical "rated" airflow but with slightly different blade shapes may create slightly different airflow vortexes that cause significantly different volumes of air to actually flow through the heatsink.
So, you see that I am trying take into account the practical overall performance of them in actual use.
A ridiculously simple test: Hold up the two "silver" sinks in front of you. Blow through them. You will find that while the "thin" unit may rattle slightly, it's generally pretty silent. The "thick" cast one however, will immediately resonate and ring quite loudly. They do this all day long! This noise is added to the air handling noise at what would otherwise probably be a relatively quiet frequency. This is just one of the many noise sources that caused the damn MDD's to be dubbed "The Windtunnel".
So, I reiterate my points:
1. All engineering solutions are a compromise between cost and effectiveness. If there was a simple way to really reduce the MDD noise without compromising reliability, Apple would have done it.
2. There are no "magic fans" that somehow work silently while still providing the same airflow. There are improved models, sure, but if you're going to play engineer and redesign something as critical as computer cooling - especially on a unit that uses a chip design that's being pushed to its absolute limit and runs too hot to begin with, you had better be prepared to survive the occasional catastrophic failure that may result.
3. Everyone's individual experience will be unique. All other factors ie. CPU load, preferred ambient room temp, personal tolerance level, furniture layout etc etc will cause some to be perfectly happy while others are insufferably annoyed.
And finally…
4. Most, definitely most of the noise comes from the damn PSU fans anyway. All of the above applies here as well but even more so. There is little or no margin for error here.
That's it…I'm pooped.
