FrostyTech has posted a review on the Arkua 6149 1U heatsink

There are essentially two options available to heatsink manufacturers looking to penetrate this potentially profitable marketplace. The first option is to construct a totally passive cooling solution which takes advantage of internal drafting and fans of a server case for air movement. These are generally the most chosen solutions by integrators since more heatsink material can be fit on top of the processor and nothing can break. In many instances, 1U server manufacturers simply use stock heatsinks with their fans removed. While this cheap solution doesn't always net the best cooling performance, it is easy for system integrators to do.

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