This COOJ Z18 build squeezes an AMD 9800X3D and RTX 5070 Metal Master into just 18 liters of silver chassis goodness. I've listed everything at the end—ASUS B850-G board, custom white braided cables, the whole setup—so you can basically just copy what we did here.
What's Actually Inside This Thing
Yeah, 18L is tight, and the GPU takes up way more space than you'd think. The white RTX 5070 Metal Master sits low, right under the NZXT Z53 pump head, with the AIO tubes routing across the card's backplate instead of getting lost behind the motherboard tray. It's a deliberate move that actually keeps things looking cleaner than you'd expect.
The silver-and-black color scheme does a lot of heavy lifting visually—silver panels outside, black internals. Two Cooler Master 12015 slim fans live on the case floor under the GPU, and the big window in front means you see everything without any mesh getting in the way of that silver finish.
The Back Side and How the Radiator Fits
The back panel is where small cases get real. You've got the ASUS B850-G I/O shield, three vented expansion slots, and one Thermalright 9025 fan all crammed into a narrow band. The 240mm NZXT Z53 radiator and its fans go on top, so the tubes have to snake down and loop around the GPU before reaching the pump. Instead of folding all that into the tray where it'd look cramped, we kept the tube path along the window. Makes a huge difference in how packed the thing looks.
RGB and Cable Management
The lighting pulls double duty here. When it's powered on, the Valkyrie memory throws a cyan-to-violet gradient, and the NZXT pump displays the liquid temp (we saw 29–30°C). Turn it off and the whole thing goes monochrome—just the silver front and window frame doing the talking.
The custom white braided modular cable set connects the Thermalright TGFX 850W PSU to everything else, with the GPU power lines bundled tight and combed out in front of the cooler. Clean, minimal, exactly what a build this small needs.
The Full Parts List
Here's what made this build happen:
| Component | Part |
|---|---|
| CPU | AMD 9800X3D |
| Motherboard | ASUS B850-G (Snow series) |
| Power supply | Thermalright TGFX 850W 80 Plus Gold, fully modular |
| Cooling | NZXT Z53 240mm AIO |
| Memory | Valkyrie 6000MHz CL28 16GB ×2 |
| Case | COOJ Z18, silver |
| SSD | Acer Predator GM7 1TB |
| Graphics card | GALAX RTX 5070 Metal Master |
| Fans | Thermalright 9025 at the rear; two Cooler Master 12015 at the bottom |
| Cables | Custom white braided modular cable set |
9 comments
Really strange: on the Cool Cube 340 case, whether it’s the LP14E with a 15mm fan frame riser or now dual MACH140 with 20mm brackets, anything above 1000 RPM gives wind noise or resonance (with 20mm standoffs there’s none). Can anyone explain? I’m exhausted by this — should I just use standoffs? That should be fine and wouldn’t cause air leaks, right?
Nearly 2K for a case, but it really does look good.
This case’s airflow should be bottom intake and top exhaust: CPU on the AIO, bottom fans pulling air in, past the GPU and the RAM, then out the top.
This case’s cooling probably isn’t great, is it?
Building in 18L is pretty painful; feels like you could swap in a Jonsbo Z20 or a Mechanic Master instead.
Beautiful.
Replying to Exus1Ai: guess I just wasn’t bold enough.
This setup looks really comfortable.
This build has to be around 15K by now, right?