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CapMousse/01-going-sff.md

Last active Apr 18, 2021
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[Going SFF] A buildlog for the Aklla A4 Pro #SFF #Aklla #Buildlog

Going SFF

Since I saw the Dan A4 and viewed different video about using this case, I always wanted to build myself an SFF PC. The idea of having a very powerful pc in such a tiny space always impress me.

But the problem with SFF PC is that parts used to build this type of PC are difficult to find and can be expensive, even more with this pandemic and components shortage. And because I already bought a Zotac RTX 3080 Amp Holo, it can't fit in the Dan A4 or even the Ghost S1. This card is simply too huge.

Using a big graphics card limits the choice for cases. Sub-10L cases with 2.5 slots in height and length of 318 mm are not common. The only mainstream case supporting this kind of GPU is the FormD T1, but have fun trying to find one.

Now enter AliExpress or Taobao: You can find many clones of different brands of SFF cases. You can get a Velka 5 clone, the Lz-a4 (4,1L) or you can try the SiriusPC T80 (10,7L), or the ZZAW B6(14,5L). If you want a more detailed list, go to CaseEnd where you can find available cases for all formats

In my case I chose the Aklla brand, who sell the A4v2 and the A4Pro, a slightly bigger and heavier A4 supporting 2.5 slots card up to 330 mm in length. The perfect fit!

The parts

Choosing parts for an SFF PC is not a small task. You must take everything in consideration: size, position, power... Not everything can fit in all cases.

As I already own a Ryzen 7 3700X, a RTX 3080 and two NVME drives, the only missing parts for my project are the motherboard, the CPU cooler, the power supply and some fans.

Choosing a motherboard

ITX motherboard can be feature limited, price can go up fast and stock can be limited. What chipset to use? B450, X470, B550, X570?

  • B450 was not cutting it: only one NVME slot and lack of features.
  • X470 use active cooling for the chipset to dissipate heat. Not great in a compact PC.
  • B550 has good features and is passively cooled.
  • X570 is great for top of the line CPU but don't offer anything the B550 already has.

After some time comparing each brand/feature, I decided to go for the Aorus B550I Pro AX : 2.5Gb/s lan, WIFI 6, Bluetooth 5, 5 USB + 1 USB-C and two M.2 ports (one PCIx4 v4 and one PCIx4 v3). Perfect for a compact machine.

Choosing a CPU cooler

CPU Cooler is more complicated: cooler clearance is only about 64 mm. Not very tall for an air cooled ~60W CPU like the 3700X. Here are the (limited) possible choice:

  • Noctua NH-L9a: good enough but can't allow the CPU to boost correctly.
  • Cryorig C7 cu: 404 can't be found in France.
  • Alpenföhn Black Ridge: the smallest air cooler with enough clearance to mount a 120 mm slim fan on top of it. Can work well with the 3700X.

You can also go for a single AIO water cooling for the CPU. Enough space is available under the power supply/GPU to accommodate a radiator with a fan.

Choosing the power supply

For the power supply, Nvidia recommends a 750W for the RTX 3080. In reality you can go lower.

For this build, with an undervolted 3080, a 650W power supply should be more than enough to power the CPU and GPU to their full capacity with some USB port used for everything you want, if you don't try to use massive USB hubs.

Many choices exist, but with the current crypto mining situation, power supply, even SFX, are not really available. I did find a Cooler Master V650 SFX Gold in a local shop, so this will be perfect.

Don't forget your Fans

As this is a very small case, small fans are needed. In this case four Arctic P12 slim. They are performing as well as the NF-A12x15 from Noctua but for only half of the price.

I will put two on the top of the case, exhausting air and one on the bottom exhausting too, to create a negative pressure and force air to cool the GPU and the CPU.

And for comfort, I will add one more fan to the CPU air cooler.

Test the parts

For fun, here is the test build with all components except the CPU Cooler. This thing is massive!

test fit

The build

Before starting, a quick review of the case : it's made of thick machined aluminum. This case is heavy ! The machining quality is really good, no machining mark, no oil... perfect !

The case

It came with a box of tools and all needed screw to make your build, the PCI Gen 3 riser, the front USB-C 3.1, mounting brackets for 2.5" drives and the power cable pre-assembled.

The case disassembled

The shell can be completely disassembled for easy access to any parts. You can also switch the position of the main center parts to allow for a bigger CPU cooler or bigger GPU. It's your choice.

Installing everything in the Aklla A4 Pro was a breeze. But before anything, we need to test fit the GPU. My GPU is 59.8 mm tall, the case documentation allow for any size less than 60 mm.

Yeah, it fit, barely but without touching the side panel, it's perfect !

Testing GPU fit

After this, installing the motherboard and the power supply was a piece of cake. Nothing is in the way, just take the time to do a clean cable management. I had to redo the GPU power cable routing because it can interfere with the top fans.

Motherboard and power supply installed

Now we only had to install this slim fan on the top. The case came with a top mounting bracket who can support dual fans and the case support one more fan on the bottom. All fans are oriented as exhaust to use the side panels as intake and force fresh air in the case.

Case with top fans

In total, the build took me about 40 minutes with 10 to remove the components from my old case and 10 other to move the central bracket from dual slot to triple slot GPU (you need to disassemble the case completely).

The build finished is heavy, but it's so small it's incredible.

Troubleshooting & temps

First thing first : the PCI riser is Gen 3 and not Gen 4.

Imagine my surprise when the first time I try to post the computer nothing did appear on the screen. Even with my motherboard set to auto for the PCI gen spec. As the GPU is Gen 4, the motherboard choose to use Gen 4, but the riser cable can't. So nothing can't be displayed.

The only solution : use my old GTX 1080 to access the bios and manually set the PCI to Gen 3. And now everything work.

There is an option to buy a Gen 4 riser cable at the right size for the case on the seller's page, but I don't need it right now.

Now for the fan curve: as the CPU heatsink is small and Gen 2 Ryzen run with high voltage in idle, the fan keeps trying to cool the CPU even if it was not in use. After some tweaking, everything was fine.

CPU Fan curve

Now, at idle, the fans are quiet and the temps are kept below 60C. Yes, idle seems hot, but nowhere near the limit allowed for this CPU.

Temps while idle

At full load, we can hear the fans. But even a MacBook Pro is more noisy than this PC. And it's not thermal throttled !

Temps with load

Cable Management

The last thing I did after completing the build was doing some cable management. The GPU power cables can sometime interfere with the top fans and a third fan can be installed under the power supply, if cables are correctly routed.

With some work, I did find a good way to move some cable behind the power supply and gain some space. A full 120 mm fan can be added under the power supply without any problem, adding more cooling to the little case.

Cable management power supply side

Cable management GPU side

Now, everything is tidy and clean, temps are even lower, especially on the GPU side and don't do much of a noise, even at full load.

And the best part : It's small on a desk !

The case on a desk

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