Final Design

            In our project, we designed an ExpressBox 6T that boasts an effective improvement in PCIe capacity as well as in the areas of cooling and acoustics (noise) while maintaining the sleek aesthetics comparable to Apple computers, the clearance necessary for hot-swapping capability, and maintaining a portability that would fit mobile consumers such as business travelers or students. As for PCIe capacity, the system holds twice as many PCIe cards than the prior Thunderbolt PCIe expansion system. While operational, the overall heat emission from each of the PCIe cards would peak at around 75W per card and thus necessitated the design of a more efficient cooling scheme which would address the overheating issue. The fact that this model is a consumer product gave rise to the appeal of silent operation and also satisfy federal EMI emission standards while remaining at reasonable temperatures. The new design was to keep the same aesthetic feel and ease-of-use as its predecessor to target Apple users and thus the 6T design incorporates many of the same look and feel features of the previous 3T.  The newly designed 6T, which had its width effectively doubled, has the capability of housing a hard drive bay as well as a separate product.

    The primary source of unwanted acoustics and cause of overheating was mainly attributed to the selection of fans around which we initiated our experimentation. Furthermore, we were limited to commercial available fans in our selection to facilitate design for manufacturability. We performed extensive testing of sound levels and flow rate on various fans of different brands to arrive at an optimal model that would fit our purposes. Also, we noticed that angling the fans downward relative to the horizontal produced more flow into the crevices between PCIe cards.

    Many of the features of the EB3T was recycled in designing the EB6T which was helpful in reducing overall time spent and cost of parts. The similarities are evident in the fact that the dimensions of the chassis remain intact besides the doubling of width.

Design

• • Width is essentially doubled from the previous EB3T model

  • Will house 6 full length and 2 half length PCIs cards

  • Aesthetics of EB3T have been kept

• • Weight is reduced through use of grommets

  • Optional back handles can be use for ease of portability

Fans

Sunon

• • Has the highest advertised and recorded volumetric flow rate at 67.1 m3/h (39.5 cfm)

  • Reduced decibel reading by reducing rpm (47 dB at 3300 rpm compared to 36 dB at 1600 rpm)

Noctua

• • Best dB to CFM ratio

  • More expensive than the Sunon fan (leaving as possible upgrade)

Angled Mounts

• Two 80mm fans will be mounted 

• Design of mounts allow for hot-swappabilty of fans

• 15° downward tilt allows for maximum airflow while reducing noise profile of fans

• To reduce the number of different parts, 2 of the same angled mounts are used with one oriented 180° to the other

Holes/Vents

• The front/back panel holes are designed so that they are large enough to provide maximum airflow and ventilation, but also small enough to minimize EMI (Electo Magnetic Interference) emissions 

• Ventilation slits were utilized above the PCIe slots to allow the hot air in between the cards to escape with little EMI emissions

Rail

• • Rail part is complicated to manufacture 

  • Using existing rail system in EB3T; one less part to manufacture, part purchased from One Stop Systems©