Littlewhitedog.com have reviewed the latest installment of copper coolers from Vantec, the CCK-6027D and the CCK-6035D. Quote:
"Both heatsinks are equipped with the micro fin design, which allows for more fins and an overall larger surface area, therefore creating better heat dissipation as air passes over them. The CCK-6035D is taller than the CCK-6027D model by 10mm (or about .394 of an inch for the "metric-challenged"). Both models also use a "Two Ball Bearing" fan, which generally has a longer MTBF (Mean Time Before Failure) than sleeve bearing fans. The specs don't show it, but during my testing I noticed the CCK-6035D fan was rotating at approximately 7336 RPM's while the CCK-6027D fan was only running at 6250 RPM's. You should also note (from the specs below) the CCK-6035D has a 0.29°C/W Thermal resistance while the smaller CCK-6027D has a rating of 0.32°C/W."