Constructing the Motherboard Tray
The Wet Bench kit's motherboard tray was designed to be modular, supporting different button, tubing, and cable routing configurations through its switchable accessory panels. It was made to support almost any form factor board on the market with mounts available for mITX through E-ATX sized boards. The tray mounts to the kit's base using the rectangular slots along the outer right and left edges.
The tray motherboard mounts are constructed from a threaded upright through the bottom of the board, held fast by a 12mm M3 plastic nut. The metal center of the upright is electrically isolated by the plastic head and the plastic nut, minimizing possibility of component or motherboard shorts. The M3 nut also acts as a spacer, so that the board does not sit directly on the surface of the tray. This allows for passive airflow under the seated motherboard, as well as proper seat height for any PCIe cards seated in the board.
The motherboard tray has three accessory holes along its right and left sides, supporting use of up to six accessory plates with the tray if desired. Primochill also offers an optional blank accessory plate that can be modified by the user for custom applications. The plates are held fast by M3 screws through their face with M3 metal nuts holding them in place under the tray.
Along the bottom edge of the motherboard tray are four elliptical holes that can be used for routing cables from mid-tray mounting devices and the PSU. Two set of holes are provided so that the pass-throughs remain available even with a larger E-ATX form factor board installed on the tray.
The acrylic mount plate sits directly on top of the motherboard tray, held in place via three of the top-mounted 12mm M3 nuts. The mount plate contains precut holes that fit over the M3 nuts so that it sits flush with the surface. The three mount points ensure that the plate remains fixed in place with a motherboard installed. The plate mounts to the tray with the card holder slots oriented above the M3 nuts. Note that the middle M3 nut does not have an upright threaded through it and is held in place by a M3 screw instead. On most motherboards, there is not a corresponding mount hole in the area of this M3 nut requiring the top of the nut to be flush with the bottom of the mounted board.
With an E-ATX form factor board mounted to the tray, you begin to get an understanding of just how large the tray is (and how it can easily support an even larger form factor board if necessary). The board easily fits in between the right and left side accessory plates without blocking access or use of them. The lower set of bottom pass-throughs remain usable as well with the upper set partial blocked by the bottom of the board. The upper part of the motherboard sits about one inch from the upper edge of the tray, allowing room to use the PCIe card mount plate.
The close-up views of the side and bottom of the board further illustrate Primochill's well-implemented design of the Web Bench's motherboard tray. The accessory plates remain unblocked and easily used. Further, the pass-through holes along the bottom of the tray remain usable in capacity – the upper set of holes are partially blocked, but still usable for flat cables, while the lower set remains unblocked and fully usable.
To hold the a mounting PCIe card in place, the feet of the card's backplate fit snuggly into the slots in the tray's PCIe card mount plate. The plate contains seven slots for holding PCIe cards and alleviates the need for a top mount-style mounting mechanism.
Going with the opposite size extreme, a mITX format factor board is dwarfed by the tray when mounted. Not only are all accessory plate and pass-through holes full accessible, but there is additional space opened up just under the bottom of the motherboard. The bottom quarter of the CPU socket cutout is visible and usable as additional cable routing space if desired. From the rear view of the mounted board, you can see that that PCIe card mount plate lines up correctly to accommodate mounting of PCIe cards to the motherboard and tray.