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--- fuss:hardware [2020/05/16 15:58] – [Powering on Fujitsu DPS-800GB-3] office
+++ fuss:hardware [2020/06/13 13:49] – [Results] office
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 Note that the connections between the molex pins have to be perfect and continuity can be verified using a multimeter, preferably by testing with the built-in continuity tester as well as measuring resistance between the pins up to a few megohms.
+====== Creating an Affordable Tray Rack Fan  ======
+Tray rack fans are meant to be inserted between the various layers of servers in a rack cabinet. Unfortunately, tray rack fans seem to be rather expensive contrasted with how they are designed to operate: a rack fan consists more or less of 4 standard $140mm$ PC fans, perhaps a switch, a potentiometer or a thermal sensor to regulate the speed. All of this comes at more or less USD100 and the price most likely gets inflated due to the equipment being considered "industrial" and meant for enterprises.
+===== Requirements =====
+  * 19" Tray - USD15,
+  * 140mm PC fan with 2 or 3 pin headers - USD 6 / piece, 24 USD,
+  * $220V$ to $12V$ step down converter,
+  * soldering, drilling equipment, etc.
+Optional:
+  * [Optional] PCB
+  * [Optional] IC pin headers
+Overall: about USD50.
+===== Design =====
+holes are drilled into the tray and the fans are mounted using nuts and screws onto the tray. The fan connectors are then connected to IC headers on a PCB that is fastened to the tray. A hole is drilled into the side of the tray and leads are drawn to the step down voltage converter in order to feed the fans. The PCB design just needs to pull $12V$ and $GND$ from the fan headers whilst ignoring the last pin which is the tachometer output signal. If a more complex design is required then perhaps the tachometer output signal could be read by an ESP microcontroller in combination with a thermal sensor.
+However, most of the suggested complexity is not required and even the PCB can be left out at the cost of severing the connections between the fan headers and then connecting the leads directly to $12V$ whilst making sure that the fans are coupled in parallel.
+===== Results =====
+{{gallery>fuss:hardware:affordablerackfantray}}
+====== Building a Better NVME Heatsink ======
+NVME tends to dissipate a lot of heat such that many heatsinks are too small to cool down the NVME module. One such case is an Intel NVME wrapped inside an "Axagon" heatsink.
+{{fuss:fuss_hardware_nvme_heatsink_axagon.png?512}}
+The aluminum heatsik heats up way too much for the Intel NVME. One solution is to extend the heatsink using some RAM coolers such as the Arctic RAM module coolers. For a good thermal contact, the paint is brushed off the Axagon heatsink and off the Arctic RAM cooler. The two bare aluminium parts are then connected using a two-part Arctic thermal compound paste.
+{{gallery>fuss:hardware:nvmeheatsink}}
+It does not matter which RAM module is used as long as it is good at dissipating heat - the Arctic RAM cooler was chosen due to the protruding lamelles that would help in dissipating the heat provided good airflow throughout the chassis.