ASRock 4x4 4800U (brickless/silent/ATX-PSU)


SFF Lingo Aficionado
Original poster
Jul 3, 2019
I was eyeing the 4800U ever since it's release... when I saw the 4X4 for just 350€ (returned) instead of 600€ (new) I just ordered it. I already had the Meanwell EPP-120S-12 and wanted to make a case where the PSU would be internal. (The board accepts 12-19V the bundled brick is 19V.) Only question was whether I could keep the stock heatsink for a very small (~1L) case:

The temperature was spiking to the thermal limit (95°C) just browsing and the fan was loud and ramping up and down... changing the thermal paste didn't resolve this issue and the only way to contol the fan (inside the BIOS) was to restrictive to be useful (the highest target temperture possible is 65°C). Or a completly fixed speed.

The best way I found to keep the noise bearable was with 'Ryzen Controller' ... for example: I let the CPU throttle BEFORE the fan goes crazy. No long term option since I need every bit of power the iGPU can deliver. Disappointing, yes these NUC's are small but from my experience the heatsink isn't sufficient and DC cord/AC cord together with the brick are annoying AND effectively double the size. So I decided that the heatsink needed to go... NOTE: I Should have tested disabling turbo before, this keeps the CPU at max. 1,8Ghz but still allows the iGPU the full 1,75Ghz... :/

I removed the fan and tested the Arctic Alpine 12 LP with the pre applied thermal paste on the heatpipes... from an old battery connector and the 4 pin of an Actic fan with 'PST' I made an adapter for regular 4 PIN fans, but with just GRD and 12V. Very happy with the results I found a heatsink that is the size of the board (100*100*18mm) ...removed the fins of the stock heatsink (heat gun @ 350°C) and glued it with thermal glue to the heatpipes after I drilled the mounting screws to be accessible and an opening for the VRM's. The temperatures arent as good as with the 12LP, but not worse than stock and quiet. No mounting for the fan on the heatsink-> best to mount it to the case.

When I took measurements for the dimensions my case needed to have I measured 125mm (for the possibility of a 120mm fan),160mm and 75mm? OR 85mm for the possibility of a 25mm fan/other heatsink in the future... And that's when I remembered the ATX-PSU measurements from my early days of SFF XD

Really didn't plan it like this, it just all came together. I haven't seen an ATX-PSU for a long time... so it took me so long. I found a defective '500 Watt be quiet! Pure Power 10 CM' on ebay... 15€! The cables and connectors can be salvaged for 12V projects the AC-inlet is already installed... XD maybe it would have been possible to keep the PSU-fan, but I already made the regular 4 pin adapter...

The base (cover) of the original case I reused because of the ideal standoff height, 2,5'' drive mount AND the two threaded M3 inserts originally meant for vesa mount... I used them to mount the base into the case. The 12V-PSU I also wanted to mount onto a base plate which than only needs two screws. I used scrap metal from the mount of a mirror and reused the ATX-PSUs insulation foil (painted black) to block of the holes on the AC-inlet side (and around the PSU).

I/O wise 2 * Type C with DP alt mode and 1* Type A from the front I/O of the 4X4 is the bare minimum(/ideal). I thought I could add 2* Type A because the 4x4 has an internal USB 2.0 header... but it is slightly smaller than the regular one :/

Together with the antenna connectors it would have held the 140mm plastic filter which I used to cover/cut out the I/O.

The filter is easy to cut and when glued to the case should be stable enough. Another option would be to de-solder the stuff from the modular-connector board of the ATX-PSU and reuse it as an I/O-shield ;)

The power button didn't arrive yet, but the 4x4 board has an 'AT-mode'... which I enabled with the connector of an old battery. Works perfectly... I'll leave it like that.

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