S4M brickless - sanding down HDPlex400


Cable Smoosher
Original poster
Aug 26, 2019
Hi Guys,

I hope this mandates a separate thread, but I have a very specific question to those electrically/electronically savvy.

As you probably know, there is an option to stick some taller cards into the S4M in a brickless HDPlex400 build by swapping the positions of the AC-DC and DC-ATX.
To do this, and not have to mod the case too much, the AC-DC unit needs to be sanded down around 2mms or so.

Here's where my question starts. I think the unit is painted with some special non-conductive layer on the outside, to make it safer and potentially less prone to passing current onto the case, just in case.
Is this actually true? Is it covered with something, or is it just the material it's made out of? Am I introducing any extra hazard by going with the sanding method?

Sorry if this is a lame/stupid question, and I really do appreciate your feedback.
I'm currently a happy owner of a S4M brickless build with a Inno3D 2060 with my own hand-made shorty cables, but really looking forward to maybe cram some power in there in the near future. I'm okay with making minor changes to the S4M like drilling some new mounting points etc. but don't want to butcher it with too much cutting.


Aug 16, 2017
I think it is powder-coated, and thus non conductive. You are right that sanding it removes that layer and make it conductive.

But you don't need to worry;
  1. No EE designer will ever connect large current/voltage source to the case. At most it'll be ground which needs to be earthed anyway.
  2. S4M inner frame is also powder-coated making it non conductive.


Case Bender
Nov 22, 2019
A quick note about sanding the PSU.

1. Since you have to take a fair amount of material off to get it to fit you will more than likely be using some sort of grinder and not a sander. I use a 4" hand held grinder and it still takes a lot of effort.

2. When sanding you will either want to remove the housing/case from the PSU or you will want to tape up all the openings in the housing to keep metal dust/filings out of the PSU.

3. If you leave the case on the PSU remember that grinding / sanding also generates heat. Again if you are leaving the case on the PSU then you will have to stop every now and then to allow things to cool down. I worked with a fan blowing on the PSU while I had it in the vice to both blow the metal dust away from the PSU and to help keep things cool.

4. The alloy that is used for the case is remarkably hard. I don't know what kind of aluminum it is or if it is hardened by the finish process but in either case it is not like raw aluminum.

5. Put tape on all the areas you are not removing material from. Again if you are doing this with the PSU in the housing also tape off the wires with a couple layers of tape. You don't want to accidentally damage a wire.

6. None of this is really all that hard just take your time and be careful to protect everything that you don't want damaged with tape.