Updated: Aug 23, 2021
Many users have already known that mATX or Mircro ATX board has more models per chipset to choose from comparing to mini ITX board and it also has more features at lower price.
The advantages of mATX board against mini ITX that I can think of are listed below.
It accommodates 4 sticks of RAM instead of 2. This can turn 4 single rank RAM sticks into high speed dual rank. It will increase 1080p gaming performance of Ryzen 5xxx CPU up to 10%
Additional 2-3 PCIe slots for sound, capture card or even 2nd GPU
CPU socket is placed further away from the edge of mainboard. This make it more compatible with larger tower cooler. The is more space between the cooler and the chassis, yield better cooling performance.
Easier to replace WIFI module. Most mATX boards don't even come with WIFI module, so you can pick the one you perfer.
More fan and USB 2.0 connectors.
It always has more VRM than ITX one at the same price. This make CPU (Especially Ryzen) run faster at stock setting. ( My MSI B550 Mortar is faster than MSI MPG B550i about 4.3%)
Even though mATX is as wide as ATX board but it's 60mm shorter. If you're using 3 slots wide card this area will be put under the mainboard and there's no space wasted.
The first case that I made for mATX board is 16L Gecko XL. Later on, some of my customer suggest that I should make it a bit wider because many people love to use large tower cooler like NH D15 or Dark rock pro 4, so I widen the Gecko XL by 37mm and now we have Gecko WXL. I also cut the ATX PSU support out so that the case won't be too large at 19 L.
As you can see from the picture above, Gecko XL is a tad taller than Gecko L and 1 L larger in volume. Gecko WXL is 4 liters larger than Gecko L.
Hardware specification that I use for this build.
CPU : Ryzen 9 5950x - Stock setting
CPU Cooler : Noctua NH D15 Chromax
GPU : Power Color Red Devil Ultimate 6900XT
RAM : Corsair Vengence Pro RGB SL 32 GB - 44mm tall
Board : MSI MAG B550 Mortar
PSU : Silverstone SX1000 SFX-L 1000W
Since most of my order are international, Gecko XL and WXL will be flat packed to reduce box volume and shipping cost. Re-assemble the case should take around 10 minutes, just follow the instruction I made. One suggestion is that you should hand tight the brass stand off and should not tight all the way in. Let them movable a bit and it'll be easier to install. Then you can tight them back later after you've placed the mainboard.
First step is to install the mainboard I/O shield and the mainboard itself by using 8 screws. Then connect front USB cable and power switch. Then remove the top panel, this will make it easier to install tower cooler and PSU bracket.
2nd step will be installing cooler's fans, 24 pin and 4+4 pins cable. Then route power cable IEC 320 from the back of the case.
NH D15 is 165mm tall when use with 32mm RAM in dual fan mode (#2 installed over RAM module). But in this case, I'll use Corsair Vengence Pro RGB SL which is 44mm tall, so this will make cooler height 177mm tall, as tall as it can be in this WXL case. The side panel will sit right over the fan. Hyper X Fury or Corsair LPX RAM is more preferable.
PSU is placed differently in Gecko WXL. The connectors are facing the side panel. This arrangement makes more cable storage room and no cable will be pressed against the back of GPU. The reason I choose SX1000 PSU is the silence. The fan won't spin even at 230W load and this is the first PSU that has no coil whining at any load. The 2.5" SSD can be placed next to the PSU.
I'm using 3 slots 62mm thick and 320mm long GPU. The front panel has to be removed to fit this GPU in. Red Devil Ultimate is no quiet GPU though, the fans when they're spinning is kind of loud. MSI Gaming X Trio or ASUS Strix is quieter. Since this case is kind of wider, plugging in the 6+2 pins PCIe cables are easy. There're room to store all the excess cables.
The bottom panel can accommodates 2 intake fans and I recommend to install them. I set all case fan speed to 900-1000 rpm and NF A12 runs every quiet. I've to put my ear next to the fan to hear it. The intake fan make Gecko WXL the lowest GPU temps among my other cases. It beats Gecko L in GPU department by 3C
Same as Gecko XL, I make mounting point for GPU sag bracket at the front. This can prevent heavy card from bending. It can avoid thermal pad separation and keep higher contact pressure between cooler and GPU die.
With 62mm card, there's still 15mm gap between the GPU and the fan.
The 19 liters in Gecko WXL is fully utilized. There're proper gap between PSU-Cooler and Cooler-Back plate. If this's ITX board, the cooler will sit right next to the back plate and reduce its performance.
Cold air will enter CPU cooler from top-front and side-front and exhaust at the back and top-back of the case. So placing exhaust fan at the top is not ideal. I prefer to flow naturally at the top.
If you have RGB cooler or GPU then the glass panel be OK. The overall CPU temperature rise by 3C with glass panel but no temp. different on GPU
Here's the temperature result with vent panel. (27 C ambient)
Cinebench R20 : 67C (66C with 280mm AIO)
Game BFV : 83C (About the same as 280mm AIO)
Days Gone : 75C
GPU : 66-68 C (303 W)
During game, side glass panel temp is not so high. It means the heat produced is diluted or removed fast enough. I keep CPU fan speed to 700-1300 rpm, this is the most quiet case I ever use.
This could be the case for people who love to use tower cooler, especially Noctua NH D15 but suffocating it, making it runs at peak performance.