Finishing the Assembly – Mounting the Motherboard Tray and Back Panel
Steps 5, 6, and 7 in the assembly guide complete the assembly of the test bench, adding motherboard mounts and PCIe mounting bracket to the motherboard tray, mounting the motherboard tray to the base structure, and mounting the rear panel to the base.
In Step 5 of the assembly instructions, you get the motherboard tray ready for use by installing the motherboard mounts and PCIe card mounting bracket to the panel's surface. The motherboard mounts are created by feeding 12 motherboard standoff screws through the tray from the bottom and fixing them in place with the M3 nylon spacers. The standoff screws are then capped with an M3 thumb nut. The thumb nut must be removed before installing a mothbard to the test bench, since the thumb nut is meant to hold the motherboard in place. The 12 provided motherboard standoffs allow the Praxis WetBench to support a variety of form factors including mITX, uATX, ATX, and E-ATX. The PCIe card mounting bracket is fixed to the motherboard tray using two M4 6mm hex head screws, fixed directly into threaded holes in the tray itself. The mounting bracket is topped with nylon M3 8mm thumbscrews, used for supporting PCIe cards installed in the system. The provided PCIe bracket supports a maximum of eight slots.
The motherboard tray contains a variety of pass-through and mounting holes for customizing the layout of the system as you like. There are vertical pass-throughs to the left and right of the CPU cut-out, supporting cable routing for a multitude of motherboard form factors. Along the bottom of the board are two additional pass-throughs that stretch the full width of the board. These provide additional cable routing for use with an ATX or E-ATX board. The holes to the lower left and right of the tray can be used to mount the included vandal switches. In the bottom center of the tray is a cut-out of the test bench logo.
The PCIe card mount bracket supports up to eight devices. Along its top are eight threaded holes for holding mounted PCIe cards in place using the provide thumbscrews. Along the bottom of the bracket are two mounting rails for fixing the bracket in place. The rails give the option of moving the bracket horizontally along the plane of the board to support a variety of PCIe port layouts on motherboards used with the test bench.
Step 6 details out how to mount the motherboard tray to the base structure. Each of the side panels contain two threaded holes four total) in their upper lip for the M4 6mm hex head screws. The motherboard tray contains four mounting holes (two per side) which fit over the hex head screws in the side panel and the motherboard tray then slides down and locks in place. The screws can be left as is for easy removal or tightened all the way down to secure the tray in place.
Looking at the back of the motherboard tray, you can see how the left and right ends are bent downwards at a 45 degree angle and then straighten out into the side mounting lip. The this bend elevates the tray providing more room for components mounted to the center panel and for cable routing purposes. The mount holes in the bottom sides of the tray are short mounting rails, big enough to fit over the screw head and then narrowing to secure the board in place as is slides forward.
The final step in the assembly of the Praxis WetBench, Step 7, involves mounting the rear panel to the base structure. The rear panel mounts in a similar method to the motherboard tray, using four M4 6mm hex head screws insert into the threaded holes on the backside of the side panel top lip. The rear panel holes on its bottom fit over the heads of the screws and pulls downward to lock into place. The screws can be left as is for easy removal or tightened all the way down to secure the tray in place. The rear panel supports mounting of up to a 360mm or 280mm radiator or up to 3 x 120mm or 3 x 140mm fans. Note that thicker fans or radiators may have to be externally mounted to the back plate rather than along it's inside.
From the front inside view of the mounted rear panel, it becomes very apparent how much space was designed into the inside cavity for radiator and fan mounting. The U-channel is approximately 25mm thick, meaning that most standard thickness radiators or fans will easily fit inside the rear panel enclosure itself, leaving even more room directly in front of the radiator for fans, tube routing, etc.
The rear panel of the Praxis WetBench is a steel panel with U-shaped folded sections along the top and bottom width of it. The U-fold creates a channel for installing a radiator or fans behind the face of the panel with mounting holes accommodating three 120mm fans, three 140mm fans, a 360mm radiator, or a 280mm radiator. You *may* be able to fit a 420mm radiator on the back panel, but it may be a very tight fit if internally mounted. Along the bottom center of the panels front is the Praxis logo. The mounting holes are located in the four corners of the back of the U-channel, big enough to fit over the screw head and then narrowing to secure the board in place as is slides downward.