The Thermaltake Tower 300 has been getting a lot of attention and it’s easy to see why. Mini-ITX performance in a case that actually has room to work. But having just finished a Ryzen 7800X3D and RTX 5070 Ti build inside one, there are a few things I wish I’d known going in.
This isn’t a review. It’s build notes – the kind of thing that only comes from spending actual time inside the case with specific hardware.
The Spec
- CPU: AMD Ryzen 7 7800X3D
- AIO: Corsair H150i 360mm
- GPU: RTX 5070 Ti
- RAM: 32GB DDR5 6000MHz
- Storage: 2TB NVMe Gen 5
- PSU: Corsair 850W
- Case: Thermaltake Tower 300
On paper a straightforward high-end gaming build. In practice, the Tower 300’s form factor forces you to think about things a standard ATX mid-tower never would.
The Thermaltake Tower 300 Build – What You’re Actually Working With
The Tower 300 is a Micro-ATX case built around a vertical layout. The motherboard mounts horizontally at the base, the GPU runs vertically, and the whole thing is designed to be viewed from the side. It looks fantastic on a desk. It does not build like anything you’re used to.
The case is genuinely compact for what it fits, but that compactness comes with consequences. Every component placement decision has a knock-on effect on something else. There’s no forgiving dead space to hide a cable run or reposition a fan. You have to think the whole build through before you start, and even then you’ll probably redo something.
Airflow – Plan It Twice, Build It Once
The Tower 300 has multiple fan mounting positions and the temptation is to fill them. That’s not always the right call. I went through three different fan configurations on this build before landing on one that made sense thermally.
The core issue is that the vertical layout means airflow paths that work in a conventional case don’t necessarily translate here. Hot air doesn’t rise the same way when your motherboard is horizontal. You have to think about where heat actually builds up with this specific combination of hardware, not just apply the standard front-intake rear-exhaust logic.
With the 7800X3D running the H150i 360mm AIO and the 5070 Ti generating serious heat under load, getting the pressure balance right matters. Too much positive pressure and you’re fighting yourself. Too much negative and you’re pulling warm air back over components that shouldn’t be seeing it. I ended up with a configuration that prioritises GPU exhaust and keeps the AIO pulling fresh air through the radiator directly, rather than recirculating air that’s already been heated.
If you’re building in a Tower 300 with a similar spec, factor in at least an extra session just for fan configuration. Test under load, monitor temperatures at each stage, and don’t assume your first layout is optimal.
Mid-build with panels off. The Corsair H150i – Short Cables in a Tight Space
The Corsair H150i is normally one of the easier AIOs to build with. The iCue daisy-chain system genuinely saves a lot of time in a normal build. In the Tower 300, the cable length becomes a genuine constraint.
The problem is routing. In a standard mid-tower you have flexibility in where the radiator mounts and which direction the pump head faces. In the Tower 300, your options are more limited, and the Corsair’s cables – which are fine for conventional builds – don’t have enough slack if you have a fan in a certain orientation.
I had to change my plans twice because of this. The first time, the connection between the radiator fans and the bottom intake fans wouldn’t reach. Once I’d sorted this, I realised that the top connector was now blocked by one of the AIO hoses. Neither issue was insurmountable, but both required stopping, rethinking, and reorienting components I’d already seated.
The fix was to commit to pump head orientation earlier in the build process – before the GPU and PSU go in – and route the AIO cables first. Don’t treat them as an afterthought. In a conventional case you can get away with it. In the Tower 300, you can’t.
Rear IO – The Case’s Biggest Quirk
This one caught me more than anything else. When the Tower 300 build is complete, the rear IO panel on the motherboard and the GPU outputs upwards – toward the top of the case – rather than being accessible from the back as you’d expect.
That’s by design. The case is built for display, and GPU looks great mounted vertically. For a desk build where the glass side faces the user, this actually makes sense. But it means cable routing for anything plugged into the rear IO – display cables, USB, ethernet – runs in an unusual direction and there’s limited space to manage it neatly. You have to remove the top cover and thread them through carefully. It can be awkward getting your hand in there and It becomes crowded as soon as a couple of peripherals are plugged in. You do have the option to move the top fans out of the way, as they are mounted to a removal bracket, but this can be hampered if you’ve already cable managed tightly.
Plan these cable runs before you finalise anything. The Tower 300 really is designed to be open to view, and using it as a conventional rear-IO machine creates friction that the case wasn’t built for.
The Finished Build
Despite the challenges, this is a genuinely impressive case to build in once you understand its logic. The end result looks exceptional – the vertical GPU, the visible radiator, and the compact footprint make it a real conversation piece.
The 7800X3D and 5070Ti combination is excellent. Thermals under gaming load are well within range after getting the fan config right, and the NVMe Gen 5 storage keeps everything moving quickly.
The Tower 300 rewards patience and punishes rushing. If you’re planning a build in one, allow more time than you think you need – especially if you’re running a 360mm AIO with Corsair’s cable lengths. And think about airflow before you think about anything else.
If you’re in Chester or the surrounding area and want a custom build in a Tower 300 or any other case, get in touch with Mat directly. Or use the PC Builder Tool to put together a spec and get a quote.
More build logs and hardware guides on the Major Custom Computing blog.
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