The article exagerated beyond belief. First off, from his graph, he compares the $30 heatsinks to the SK6 (predecessor to the SLK-600, but I believe the only difference between the two are the fan clip mechanisms), which, as you pointed out, is no where near $80. In fact, the original SK6, without shipping, is $26. The SLK-600 is $38 without shipping (if you add shipping to that price, you'd have to add shipping to the AX-7/GIII for a fair comparison). Even adding an 80mm fan (which I hear you can ghetto-rig onto an SK-6 without an adapter, but not with an SLK-600) would push the price to what? $10 more for a grand total of 36/48 (SK-6/SLK-600)? Hardly $80 vs. $30. The Swifttech wasn't in the comparison. The article tried to debunk the idea of buying a high performance heatsink (in this case, the SK-6) and using a lower RPM fan because it's so much more expensive, which it really isn't. In fact, using specifically the SK-6 and not the newer SK-600, it's the same price (possibly lower if you buy a cheaper fan, like the ever popular Panaflo L1A for ~$4).
I didn't explain the fan thing very well. First off, what I meant by quality fans are ones with good CFM to dB ratio at low RPM, such as most Papst fans. The complete retail unit of the AX-7 comes with a high output delta. Obviously, that's a fan designed for pure CFM with no thought to noise. Now Thermalright advertises the AX-7 as being a heatsink "Minimized noise to performance ratio with low speed fan" (on their product page), yet they packaged it with the Delta. So I brought up the point of bringing in a different fan. That Delta used had a pretty good ratio, but unfortunately even 7-volted, it wasn't that quiet. 38dB for an office environment seems pretty high to me. I've heard most people tend to aim for at highest 35dB, usually 30dB. And that's total system sound, not just one fan. So a better comparison would've been with fans of much lower dB, where that Delta screamer could've even reach (possibly 5v would work, but it might still be too high). So the only choice is to buy a different fan. With something besides the 80mm Delta and readings taken at dB much lower (around the 21-26dB range), the comparison wouldn't be valid (unless you also stuck a GIII with a lower RPM fan or volt-modded it).
In terms of CFM/dB, 60mm fans are 0.8 CFM/dB or below, where as 80mm fans are usually 1.1 CFM/dB (1.1 is pretty pathetic, 1.2 is probably closer to average) and above. That's not even RPM at the same RPM, that's just efficienty ratio. Take for instance, the 60mm Delta EHE, 50.1CFM/54.5dB (8000RPM), one of the best 60mm fans in terms of CFM/dB ratio. Now take an 80mm Delta, 80.16 CFM @ 52.5 dBA (5700RPM, same as the graph). A little more than 5% difference there. I'd imagine 70mm fans fall somewhere inbetween.
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