PCs are modular.
We can replace the CPU, GPU, RAM, storage, cooling, and even the motherboard. But one part of the desktop PC has remained surprisingly rigid: the relationship between the case, the motherboard, the graphics card, and the power supply.
Small-form-factor PCs make this especially obvious.
Today, building a powerful compact PC usually means working around the limitations of existing standards. You need an SFX power supply, custom cable routing, tight clearances, carefully selected GPUs, and often a case designed around one very specific hardware combination.
What if we stopped treating the case as a fixed box and started treating it as a modular platform?
The Problem With Modern SFF PCs
Modern SFF systems are impressive, but they are often difficult to build and even harder to upgrade.
A typical compact gaming PC has to fit:
- a Mini-ITX motherboard,
- a desktop GPU,
- an SFX or SFX-L power supply,
- CPU cooling,
- storage,
- cables,
- and enough airflow to keep everything stable.
The power supply is particularly awkward.
It occupies a significant part of the internal volume, generates additional heat, requires relatively thick power cables, and limits how the GPU and motherboard can be positioned.
This is strange when you think about it.
Laptops, mini PCs, monitors, networking hardware, and many professional devices already use external power supplies.
Why should a 300–500 W desktop PC always carry its AC power conversion hardware inside the chassis?
Move the PSU Outside
Imagine a different architecture.
Instead of putting a traditional ATX or SFX PSU inside the computer, the system uses an external high-voltage DC power supply.
For example:
230 V AC
│
▼
External PSU
48 V DC
│
│ 1–2 m cable
▼
PC
│
├─ 48 V → 12 V
├─ 12 V → CPU
├─ 12 V → GPU
├─ 12 V → 5 V
└─ 12 V → 3.3 V
At 400 W, a 48 V link only carries roughly:
400 / 48 ≈ 8.3 A
That is much easier to transmit over a cable than several hundred watts at 12 V.
The internal system would then use a compact DC/DC power board located close to the motherboard and GPU.
This has several advantages:
- less heat inside the chassis,
- less internal volume dedicated to power conversion,
- shorter internal power cables,
- simpler airflow,
- easier packaging,
- and potentially much smaller cases.
For something like a dual-fan RTX 4070 and a Mini-ITX motherboard, a system around 5 liters becomes realistic without extreme compromises.
But the More Interesting Idea Is Modularity
External power alone is not the real point.
The bigger idea is to create a new modular standard for small desktop PCs.
Let us call it, for now:
MSFF — Modular Small Form Factor.
Instead of defining one fixed case size, the standard would define interfaces.
For example:
Motherboard module
ITX / mATX
GPU module
Short / SFF / Full-size
Cooling module
Slim / Standard / Performance
Power interface
48 V DC
Chassis interface
Standardized mounting grid
The case would no longer be one monolithic structure.
It would be a set of interchangeable structural modules.
One Platform, Multiple Sizes
A possible product family could look like this:
MSFF-S
Designed for:
- Mini-ITX
- short dual-fan GPU
- low-profile CPU cooling
Approximate volume:
4–5 liters
MSFF-M
Designed for:
- Mini-ITX or micro-ATX
- medium-size GPU
- larger CPU cooler
Approximate volume:
7–9 liters
MSFF-L
Designed for:
- micro-ATX
- full-size GPU
- performance cooling
Approximate volume:
10–12 liters
The important part is that the versions share the same design language and as many components as possible.
For example:
- the same external PSU,
- the same DC/DC board,
- the same panel mounting system,
- the same feet,
- the same fan modules,
- the same structural connection points,
- and possibly the same front and rear I/O modules.
Only the frame dimensions and a few structural parts would change.
Upgrading the Case Instead of Replacing It
This changes the way we think about PC upgrades.
Today, an upgrade path can look like this:
New GPU
↓
Need more power
↓
New PSU
↓
GPU no longer fits
↓
New case
In a modular system, the same upgrade could become:
New GPU
↓
Install longer GPU frame module
Or:
Mini-ITX → micro-ATX
↓
Replace motherboard tray
↓
Install larger frame section
The user keeps the rest of the system.
The chassis itself becomes upgradeable.
That is a natural extension of the philosophy that made PCs successful in the first place.
Small Components Should Fit in Larger Configurations
Backward compatibility would be important.
A larger MSFF frame should still support smaller configurations.
For example:
- an ITX motherboard should fit inside an mATX-compatible frame,
- a short GPU should fit inside a long-GPU frame,
- a small cooling module should work inside a larger chassis.
This already happens to some extent in traditional PC cases, but a modular standard could make it deliberate and predictable.
The user could start with:
ITX + RTX 4070
and later move to:
mATX + larger GPU
without abandoning the entire platform.
Why 48 V Makes Sense
A higher-voltage DC bus is particularly interesting for compact systems.
At the same power level, higher voltage means lower current.
Compare a 400 W system.
At 12 V:
400 / 12 ≈ 33 A
At 48 V:
400 / 48 ≈ 8.3 A
Lower current means:
- thinner cables,
- lower resistive losses,
- smaller connectors,
- less heat,
- and easier external power delivery.
The DC/DC conversion would happen close to the components that actually need 12 V.
This is conceptually closer to how many modern industrial and server systems are designed.
Existing Standards Already Solve Parts of This
None of the individual ideas are especially radical.
We already have:
- Mini-ITX and micro-ATX motherboard standards,
- standardized PCIe interfaces,
- compact GPU size classifications,
- external power adapters,
- DC/DC conversion,
- riser cables,
- removable motherboard trays,
- modular cases,
- and 12 V-focused power architectures.
What is missing is a standard that combines them into one coherent platform.
The interesting opportunity is not inventing every component from scratch.
It is defining how they fit together.
The Case Should Be a Platform
The traditional PC case is mostly passive.
It is a box with mounting holes.
A future SFF chassis could instead behave more like a mechanical platform.
Imagine a standardized structural grid where manufacturers could build:
- GPU modules,
- radiator modules,
- storage modules,
- motherboard trays,
- fan modules,
- front I/O modules,
- and power modules.
A case manufacturer could sell the base platform.
Other manufacturers could sell compatible modules.
The result would be closer to an ecosystem than a traditional PC case.
A 5-Liter Desktop With Standard Components
One of the most interesting use cases would be a very small gaming desktop built almost entirely from standard PC hardware.
For example:
Mini-ITX motherboard
Desktop CPU
32–64 GB RAM
M.2 SSD
Dual-fan RTX 4070
External 48 V PSU
Internal DC/DC board
Without an internal SFX power supply, such a machine could potentially fit into a chassis around:
245 × 190 × 100 mm
That is roughly:
4.7 liters.
It would still use a standard desktop CPU and a replaceable desktop GPU.
That is much closer to a console-sized computer than a traditional desktop tower.
But unlike a console, every major component remains replaceable.
There Are Trade-Offs
This would not be free of problems.
A modular standard would need to solve:
- high-current DC/DC conversion,
- transient GPU loads,
- connector specifications,
- safety requirements,
- EMI,
- thermal design,
- mechanical tolerances,
- PCIe riser compatibility,
- and manufacturer adoption.
There is also a danger of making the system too modular.
If every dimension is adjustable, the chassis becomes unnecessarily complicated.
The goal should not be infinite configurability.
The goal should be a small number of standardized modules that cover the majority of useful configurations.
The Bigger Question
The desktop PC became successful because it separated components from the machine itself.
The CPU is replaceable.
The GPU is replaceable.
The RAM is replaceable.
The storage is replaceable.
Even the motherboard follows standardized dimensions.
But the chassis and power architecture are still treated as relatively fixed structures.
Maybe the next step in PC modularity is not another motherboard format.
Maybe it is a standardized relationship between the motherboard, GPU, chassis, cooling system, and external power supply.
PCs are already modular.
The PC itself should be modular too.
