Review on Coolerguys Dual USB Fan, High Cooling Capacity, 50Mm, High-Performance Efficiency, Dimension: [1.97 X 0.79 X 1.97 Inches], 5V, Ultra Quiet Cooling Blower Fan by Jason Tinnen

There are already a lot of reviews that cover most everything, however for those who may be more of the hardware hacking variety, this review is for you. First, these two fans feature a very nice dual ball bearing design. Due to this and the RPM speed, they run silently (meaning as silent as fans go). A bonus feature is that you can mount the fans in either a vertical or horizontal position. Although as the specs show, these are not powerhouse designs and work best at removing ambient heat from a closed/relatively-closed space. I had plans to use these fans as part of a custom box that houses various PCB boards. One was going to be used as an exhaust fan on the top of the box, with another providing airflow over a group of heatsinks using negative pressure below that. I found that they work best as exhaust fans though, so my plans changed in that one is seated on top and the other is providing exhaust based cooling to the lowest cage, which houses the custom PSU. The heatsinks do a good job on their own, however as I'm using custom chips and their layout may change, I want to avoid removing them to place a generic liquid-cooling block on top and instead find a fan-based solution for actively cooling the passive components.Also as one would expect, the fans run at one default speed. I tried adjusting the power to the USB output, however instead of slowing down, at 4v the fans just shut off. I ended up removing the USB lead and plugged the fans into two different sockets that were already connected to temperature probes in the desired areas with a control board to handle it all automatically. Currently the fans run independently at either 0v (off), 1.5v (low), 2.5v (medium) or 3.5v (high), all with the default amps. The fans should run fine at 5v each (aka double the default power), however as they are currently either off or running at 3v - 4v combined, I have decided to not push it and end up with 1 or 2 fried fans.