6

When building a custom case for a computer that will be mounted on the wall, hanging, suspended are there any special considerations for the PSU or grounding?

Assumption 1 – I assume the MB will need to make contact with the metal case and using brass standoffs are fine. Because the custom 'wall case' is mostly metal (20×20 extrusions), those standoffs can safely be mounted to the metal case, making metal-contact with the MB as one would in a normal case.

OR – In this situation should Nylon standoffs be used instead to insulate the MB from the frame? (Why do I think this: because of interference, RF, avoid making the computer into an antenna, etc.)

Assumption 2 – I assume the PSU will need to make grounded metal-to-metal contact with the case as well just like a normal build.

OR – In this situation should washers or nylon be used to insulate the PSU from the case since it's wall mounted? (Why do I think this: because of RF and to avoid static problems or making an electromagnet.)

Clear acrylic will be used for a MB bracket and a PSU bracket (to make it easier to secure those components to the 20×20 metal extrusion frame), which brings up the following considerations:

  • If those custom acrylic mounting brackets will insulate the PSU from the metal case, then is additional grounding is needed to ground the PSU to the case?

  • If those custom acrylic mounting brackets will insulate the Motherboard from the metal case, then is additional grounding is needed to ground the Motherboard to the case?

  • Neither the MB nor the PSU needs to be grounded to the case, ergo: mounting them to acrylic frames with no metal contact or additional grounding is fine.

  • Conclusion A: None of the above matter? I.e., ground or no ground, a high quality PSU and good MB will be fine mounted in a wall case because the wiring is grounded through the PSU->Plug->Outlet->Home wiring – therefore, no special considerations are needed. RF interference, static and electromagnetism will not be a problem for a suspended wall mounted computer system and each component can be insulated from the others with nylon standoffs, acrylic brackets, insulating washers; even the frame itself could be plastic or acrylic.

  • Conclusion B: All of the above matter? I.e., following the path of the ground from the power outlet through the computer system => the PSU, the MB and the case should all be connected and grounded, a metal frame is a good idea, metal mounting plates are better than acrylic and nylon should be avoided.

Let us assume in all cases here that the unit is "floating in space" (connected only by the PSU power cord) and the wall itself may be glass, metal, wood, rubber or simply "air" if the unit is hung from wires. Let us also assume that audio speakers will be connected and that Wi-Fi, cellphones and radios may be in use near the unit.

In closing: Which of these conclusions is true (A or B), and which, if any, of my assumptions (1 & 2) is incorrect?

Because this was "closed" lets make the 4 questions "more clear" for the admins here... I am asking "how to properly ground the PSU and the Motherboard on a WALL HANGING custom computer.

There are 4 simple questions:

  1. Do I need to ground the Motherboard to the case using metal screws?
  2. Do I need to ground the PSU using metal screws?
  3. Can I use Nylon on the Motherboard Risers?
  4. Can I use Nylon on the PSU bracket?
Christian Žagarskas
  • 179

3 Answers3

2

Electrically and from an RF standpoint, there is nothing special about a computer being on the floor, on a table, on a shelf, or on the wall. Higher up (regardless of how) means the radio waves have further line of site, but that's it. And there will be some difference if e.g., the table is metal, as that may reflect radio.

The big difference is that your case isn't fully metal. The metal enclosure blocks a lot of RFI, and standard components are designed to be in one. So your non-metal case might have your computer exceeding permitted radio emissions, regardless of whether it hangs from the ceiling or sits in the floor. Only someone with test equipment could tell you for sure.

derobert
  • 4,572
1

Conclusion A is the answer. Basically all of the grounding is done through the cable from the main power supply cable between motherboard and PSU via the 24 pin connector. The PSU is then grounded through the AC power cord to the ground lug on your outlet.

DrZoo
  • 11,391
0

The ground wire wire from the wall outlet connects to the ground pin on the computer's power cord. This in turn connects to the PSU. The black wires for the various power connectors in the PSU are connected to the ground. For safety, the metal case of the PSU is also connected to ground.

You will notice that in typical computer builds, the structure is all metal and all those metal components are physically in contact with each other, either by directly touching and/or with metal screws. This means all the bare metal components that someone can touch are grounded and should be safe to touch if there is a short.

Does this mean you have to have everything made of metal and touching? If everything is connected properly and nothing is shorted, then no, it does not have to be. Technically speaking, all you need is the PSU to be connected to the motherboard by the connectors. However, connecting all the grounding points on the PSU, case, and motherboard electrically does make it safer.

Edit:

Yes, you can do a hanging computer. So your conclusion A is correct.

  1. No
  2. No
  3. Yes
  4. Yes
Keltari
  • 75,447