The following Application Note describes the mechanical specification of the ATX form-factor motherboard, including mounting hole placement, component height constraints, physical size, connector placement, CPU and memory modules placement that should be taken into consideration when D14 based system has been created. The main two vital concepts to keep in mind when selecting a motherboard for the D14 chassis are the layout and height consideration.

Height
D14 has 41.8mm internal height. If a system has to fit in the D14 space, the height you have to work with inside the chassis will be less than 41.8mm. Also please keep in mind there is a certain amount of space required between the components and the chassis to prevent a short circuit. The motherboard mounting area on the bottom of the D14 chassis does not have a non-conductive lining to prevent the motherboard from short-circuiting with the bottom of the chassis. The D14 provides 5mm clearance between the bottom and motherboard surface. Is is quite safe distance, however the D14 chassis does not fit motherboard that comes with 4mm and higher components placed on bottom surface. Also, the D14 chassis does not fit motherboard that comes with 35mm and higher components placed on top surface (Chipset Heatsink, as shown on the picture on the left). 35mm is a maximum height restriction. Keep in mind a safe space between the components and the chassis. Consider 2U or above rackmount chassis if you use motherboard with big chipset heatsink. Some other motherboards can also fit with slight modifications. One typical component that prevents proper mounting in the D14 chassis is the vertical audio port that is found on modern motherboards. This audio port is slightly higher than the chassis and will not fit in the D14 chassis. For novice users we recommend not to use these motherboards. The motherboards with these audio ports can be easily modified to fit by applying some minor professional services (as left animation shows). However, these professional services are beyond the scope of this application note and will not be discussed here. Disclaimer: DV Industrial Computer Ltd. is not liable for any damages caused by this application note. Modifications to any original equipment are not recommended and will void the warranty. All services described in this application note should be performed by licensed professionals.

I/O Shield (Backplate) compliance
Standard ATX I/O Shield is too high to be used in 1U case. Therefore, there is special designed shield equipped with the D14. This Shield is mounted at the motherboard, unlike regular shield that is clipped to the chassis. Refer to Detailed information on shields to select proper shield. If you have in mind motherboard that does not have appropriate shield, please indicate type of your motherboard and inform us. We can produce necessary shields in advance and will have it in stock.

Size and Mounting Holes Location
The maximum allowable board size for the D14 chassis is 305mm x 244mm, the same size as an ATX board.
Not all ATX board mounting locations have been implemented for the D14 chassis to achieve full ATX 2.01 compliance and to provide proper support for the board in these areas. To accommodate motherboard, a non-removable standoff (red marked on the left picture) has been used. If it is desired to implement a board mount in absent standoffs (blue marked), a self-adhesive fasteners should be used to avoid problems with boards that require using these mounting holes. And vice versa, the location of mounting standoffs may not accommodate motherboard that is available on the market. Chassis standoffs in these positions should be removed, because damage to traces on an motherboard may occur. Of course, we recommend to avoid such non-standard motherboards.

Layout
In order to select motherboard with required layout, it is necessary to review air-cooling of the D14. The power supply unit of the D14 chassis, rather than blowing air out of the chassis, as in most competitor 1U chassis, provides airflow through the chassis and across the processor. Note, the CPU is cooled from a passive heatsink which, it is clear, has been blown by cool blast (blue arrows, shown on the left). Specially disposed air intake diffuser has been placed between CPU and PSU in order to concentrate this blast. So, the CPU should be located near PSU (yellow area, shown on the left). The exact location of the PSU connector and memory modules is not specified. Of course, they should be located away from the main path of air.

Install the CPU as instructed in your motherboard manual. Please remember to apply the thermal grease on the CPU or the CPU will overheat.

Use only specially designed all-copper 1U CPU heatsink as a CPU cooler. Note, the CPU is cooled from a low profile passive (without fan) heatsink which has been blown by blast from 4 fans of PSU. Adjust the airflow by precise positioning of intake diffuser (shown red on the left picture) to concentrate this blast. Take care of diffuser to be opposite CPU. Orient the heatsink gills to set the path of airflow in the proper direction (see picture on the left). In order to eliminate air leakage use self-adhesive foam band and foam pad. Thin (3mm) foam pad should be used to prevent air from flowing over the top of the heatsink. It must be attached to the top of the heatsink in order to have sufficient airflow through the heatsink. Place the pad on the heatsink fins. Also, stop air leakage on each side of heatsink near diffuser. In this case use foam band a 10~20mm thick. The heatsink will not perform properly without sufficient airflow. Because of the fin density, air will flow around the heatsink if allowed. The foam parts prevent air from flowing over and around the heatsink, and force the air to flow through it. Failure to attach foam parts may cause the processor to operate out of specification and reduce it's life expectancy.

Leave airflows inside the D14 free from wires, memory modules etc. Slightly bend the motherboard power connector's wiring (as shown left) to ensure a better fit. Do not bend these wires when the connector is plugged into the motherboard. Doing so will damage the motherboard. Repeat for 12V auxiliary power cable. Put all cable ties down to minimize airflow resistance. Adjust the airflows of cool and warm air outside of the D14 with corresponding airflows inside the case.

Riser card 1U1FR (1U1FR-e1, 1U1FR-e4) is used to change the insert direction of I/O card to the slot of motherboard by 90 degrees. The I/O card is plugged into the riser card and resides parallel with the motherboard. The D14 case and 1U1FR (1U1FR-e1, 1U1FR-e4) riser card provide expansion for one I/O card. Picture at the left shows the PCI slots location on a 7-slots standard ATX form factor board (starting from the left): PCI slot-1, slot-2, slot-3, slot-4, slot-5, slot-6 and PCIe (or AGP) slot-7 (On a Micro ATX board, there are only PCI slot-4, slot-5, slot-6 and PCIe (or AGP) slot-7 ). The position of slot-6 corresponds with the horizontal cutouts of the D14 chassis. Keep in mind that your motherboard should have PCI (PCIe) slot-6 in order to provide riser card plugging. Also, keep in mind a safe space between components on top surface of I/O card and the cover of chassis. Use a non-conductive self-adhesive bumpone to prevent the I/O card from short-circuiting with the cover of the chassis.
Riser card is supplied as option, but it is advisable to order required riser card together with chassis.