"KalmX AMD Edition" - RADEON RX 6400 Passive Cooling Mod

REVOCCASES

Shrink Ray Wielder
Original poster
REVOCCASES
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Apr 2, 2020
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someone on Reddit asked me if I could do something similar like my RTX A2000 Passive Cooling Mod but for AMD... now what could be better suited for a fanless AMD GPU than the very efficient RX6400, delivering GTX 1650 performance at a TBP of just 53W... that said, I can't quite understand why no manufacturer offers fanless options for this card - perhaps it's too much of a niche to make enough profit...

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anyways, here comes the mod...

I chose one of the Low Profile RX6400 cards (made by XFX, Powercolor, Sapphire) so that less of the PCB would block natural airflow through the passive cooler

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next I machined a coldplate out of 3mm copper... this covers the GPU die & memory chips and will be used for mounting...

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the cooler itself will again be an ACCELERO S1 which is solder onto the coldplate with 138C solder paste

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first applying the solder paste, clamping it together and then backing the whole thing for a few minutes until the solder melts...

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note that the GPU die is about 0.2 ~ 0.3mm higher than the memory chips - to compensate the height difference you need to use some very soft and thin thermal pads or alternatively you can put a good drop of thermal paste on the memory... if you use pads, they really must be very soft because you can't (shouldn't) apply to much mounting pressure...

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last but not least, mounting the new passive cooler - I used the springs from the original XFX heatsink, plus four M2.5x8 screws...

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and here is the finished mod:
  • GPU: XFX RADEON RX 6400 4G
  • Cooler: ACCELERO S1 & CNC machined coldplate
  • Dimensions: ca. 2 Slots, 135mm height, 220mm long

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REVOCCASES

Shrink Ray Wielder
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now lets see how it performs compared to the stock cooler...

1) Stock Cooler, 1h stress test, 20C ambient

Screenshot 2023-04-19 113056.jpg

2) DIY Passive Cooler, 1h stress test, 20C ambient

Screenshot 2023-04-21 105749.jpg

I have attached the drawings of the coldplate to this post for the DIY community - it should be compatible with all LP RX6400 cards - enjoy!

If you're not comfortable doing this mod by yourself, I've listed the pre-modded card in the trade section!
 

Attachments

  • RX6400 Passive Coldplate.zip
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b_force

Average Stuffer
May 28, 2019
67
18
I have the same XFX RX6400 and have been searching around for some custom cooling solutions.

First of all, I think your mod is really incredible!
It also really motivates me to do something similar (although I don't think my CNC is powerful enough)

I have been trying to cool this little card down.
Currently I am using it in a very small build, but unfortunately the little GPU just gets very toasty.

A simple solution would be mounting a 80-120mm on the side, but unfortunately I only have about 10mm clearance.

I don't need to go completely passive, just some better (and more quiet) fan would be better.
I was wondering, would one of those old Zalmen VF700's be good enough?

@REVOCCASES do you have any idea how different the thermal performance would be by making the adapter plate out of aluminum instead? Obviously it's not possible to solder both together anymore at that point.
 

REVOCCASES

Shrink Ray Wielder
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@REVOCCASES do you have any idea how different the thermal performance would be by making the adapter plate out of aluminum instead? Obviously it's not possible to solder both together anymore at that point.

a 3mm aluminum plate should also be fine if your CNC has trouble with copper... perhaps you could mount the Zalman on it using thermal paste and screws... alternatively you could buy a aluminum heatsink and mod it to make it fit on the RX6400...

1688434339255.png
 

b_force

Average Stuffer
May 28, 2019
67
18
a 3mm aluminum plate should also be fine if your CNC has trouble with copper... perhaps you could mount the Zalman on it using thermal paste and screws... alternatively you could buy a aluminum heatsink and mod it to make it fit on the RX6400...
Do you think those Zalman heatsinks will be enough to cool the whole thing?
It has been a while, and I can't remember what "TDP" they were using back in the day.
(getting old lol)

I will have a second look on the heatsink design, the PCB requires quite some attention for clearance.
Otherwise some kind of adapter plate would work there as well.

Edit: So I just wanted to show some progress with sobe low profile fan adapters I made. But unfortunately by pulling out the fan adapter board, I accidentally pulled the Rx6400 with it. Now it's not working anymore. 😭(I should have know better I know).

Does anyone know the common fail state when that happens? I find it hard to believe that the gpu I itself us fried.
Worth troubleshooting the issue and maybe replacing some parts otherwise. (I have years of experience in smd soldering and pcb design).

Anyway here is a first proto of the low profile fan adapter. This is with 40mm fans, 60mm would just fit as well (just slighly out of the official design specs)

Edit2: for some reason image won't upload?


 

REVOCCASES

Shrink Ray Wielder
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Apr 2, 2020
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I guess the Zalman should be sufficient since it's just a 54W GPU

Oh no... sorry to hear that with your RX6400... can you spot any obvious damages / fried components?

Your fan adapter looks really good, nice job!