Concept Mid-range gaming in under 3 litres: the GD299


Caliper Novice
Original poster
Aug 22, 2019
Hi all,
I would like to introduce the concept and working prototype of a 2.99 litre mini-ITX case, capable of housing a mid-range graphics card, and test the appetite of the market for such a case. If this interest you, it would be great to hear your comments in the reply section or e-mail me at:

Ladies and gentlemen, the G-Design GD299:

The project has been born from an obsession to build a sub-3 litre SFF case capable of encompassing widely available mid-range gaming PC components. This shaped my challenge. These were my objectives:
  • Under 3 litres in volume
  • Compatible with graphics cards and processors capable of mid-range gaming performance
  • Use of widely available components
  • No reliance on any single product
  • Upgradable
What makes the GD299 different?
The GD299 enables mid-range gaming performance in a sub-3 litre case, whilst being upgradable and compatible with widely available components. The unique arrangement of the internal components inside the GD299 has enabled the volume to cross below the 3-litre threshold, beyond that achieved by more traditional component layouts. There are some incredible projects in existence that have pushed the 3-litre boundary for a gaming PC capable of housing a discrete graphics card. However, they tend to rely on the use of either low profile graphics card or specialised components with limited availability, presenting a risk of the case becoming redundant if such components are discontinued.

Who is the GD299 for?
The GD299 is for those requiring mid-range gaming performance in the smallest possible volume, allowing desktop upgradability and compatibility with widely available components, but who are willing to accept some limitations in performance, storage and component choice imposed by the small size of the case.

It will not be for everyone, but the capacity for the case to encompass mid-range gaming components should still allow for acceptable gaming performance for many users. For those requiring higher performance in a compact SFF case, but where such small size is less crucial, there are certainly more suitable options available (e.g. Dan A4, Velka 5, the legendary NFC Skyreach S4M).

GD299 specifications:
  • Volume: 2.979 litres
  • External dimensions: 184 x 176 x 92 mm
  • Materials: 1.5 mm stainless steel sheet, joined by steel rivets and screws
  • Finish: likely to be powder coated or unpainted
Size comparison to other popular SFF cases:

Source of CAD files:
Dan Case A4:
NFC Skyreach S4 mini:

Hardware compatibility and limitations:
Achieving such a small volume is only made possible by limiting the size of the compatible components. The overall performance will be limited by the total system power draw and power supply. Compatibility of individual components is as follows:
  • Motherboard: ITX only. Motherboards with large shrouds and heatsinks are expected to be incompatible when using dual slot graphics card due to clearance constraints. A list of compatible motherboards will be provided. Please note: due to size limitations, the case does not allow for the installation of motherboard I/O shields.
  • Graphics card: dual slot, length up to 174 mm.
  • Processor: limited by power supply and cooler performance.
  • Processor cooler: Height under 35 mm if using discrete graphics card. Blower style CPU cooler strongly recommended due to limited clearance between fan and graphics card.
  • Power supply: Compatible with pico PSU (e.g. Mini-box 160XT, HDPLEX 200W DC-ATX) and HDPLEX 400W DC-ATX. Requires external AC-DC adapter (power brick). Please note: the GD299 has the internal capacity to fit the HDPLEX 250W GaN ATX power supply. However, due to the size of the case, there are limited options for safely mounting the C14 panel mount for the 10-240V AC input. Use of the HDPLEX 250W GaN ATX power supply is therefore not recommended.
  • Storage: motherboard mounted m.2 drive only.
  • Memory: low profile RAM modules only (height <38mm).
  • Mounting holes for up to 2 x 40 mm case fans.
  • 5 cm PCI-e riser cable required.
  • 24 pin ATX motherboard extension cable required (the cable provided with the HDPLEX 400W DC-ATX ).
In contrast to other SFF cases in the 4 – 5 litre size bracket, the main drawbacks are the potential incompatibility with certain motherboards, limitation to blower style CPU cooler (and associated increased fan noise) and lack of space for 2.5/3.5 drives when using a discrete graphics card.

Example builds:
  • Intel i3 10100F CPU and Nvidia GTX 1650 graphics card powered by Minibox 160XT pico PSU and 192W AC-DC power brick
  • Intel i3 12100F, Nvidia GTX 1660 Super powered by HDPLEX 200W DC-ATX and SlimQ 240W GaN AC-DC power brick
  • Intel i5 12400F, Nvidia RTX 3060 powered by HDPLEX 400W DC-ATX and Dell 330W AC-DC power brick
My current build:
My prototype GD299 houses a MSI B150i-ITX motherboard, Intel i5 6500 with Dynatron K199 cooler, Nvidia GTX 1660 Super, 16Gb Corsair Vengeance LPX (low profile) DDR4 2400 RAM, 1Tb m.2 NVME SSD and is powered by a Dell 330W external power brick with HDPLEX 400W DC-ATX adapter. Performance under stress testing (Furmark + Intel Burn Test): CPU max temp: 72 degrees C, GPU max temp: 63 degrees C, Max noise (measured at 30 cm): 49.3 dBA, Max power draw: 216W (270W with 80% efficiency).

Unfortunately, I purchased a single fan RTX 3060 to test prior to posting this, but the system keeps switching off above ~230W – my power supply might be on it’s way out!

What's next?
If there is sufficient interest, the next steps would be to pursue small scale manufacture. Evaluation for compliance with UK trading standards and General Product Safety Regulations would be undertaken. This includes a product risk assessment. Depending on the outcome of the risk assessment, testing and feedback, modifications to the design may be undertaken to improve safety, performance, aesthetics and structural integrity and reduce production costs. I'm also not 100% taken with the vent holes, so possibly some restyling needed there! As the objective is to produce a sub-3 litre gaming PC case, modifications resulting in the external volume exceeding 3 litres would not be undertaken.

Ongoing testing is required to provide recommendations on compatible components.

The case would initially be priced between $/£/€ 200-300 (+ shipping), depending on demand and therefore scale of manufacture.

I’d love to hear what you all think in terms of the design, the level of demand for the concept given the limitations and opinions on price. Are there already any sub-3 litre cases on the market capable of meeting the same performance using widely available components that I've overlooked? Does it appeal to anyone else or just me?! Please either comment below, or e-mail me at