Xi3 is demonstrating a modular computer called the Piston Pro at CES 2013, and if rumours are to be believed it could help understand Apple's next direction for the Mac Pro.

It is notoriously difficult to upgrade the internal components of Apple's computers. The new MacBook Air computer, for example, has no internal upgrades available. You can't change anything: not even the hard drive or RAM, let alone the graphics card.

One exception is Apple's Mac Pro computer, which has historically allowed users to upgrade hard drives, RAM, graphics cards, and add internal PCI cards. The Mac Pro is designed to make these upgrades as easy as possible, with snap-connecting parts, and as few screws as possible (you don't even need a screwdriver to open the computer). Although changing the motherboard and upgrade the processor has always been more of a challenge.

Why the interest in a Modular Mac Pro

Modular computing is a technology that is starting to arrive in the market. The idea is that instead of having a single computer with parts you slot inside, that the individual components are housed inside their own casing and are slotted together.

So instead of buying the box and slotting raw components inside, you'd buy a number of smaller boxes 'cubes' and connect them together.

See also: New Mac Pro Release Dates Rumours and leaked images

True modular computers can have parts added, and removed, without interrupting their operation. So if you have two 4GB memory 'cubes' for 8GB RAM. if you removed one of the cubes the computer would keep theoretically keep running.

Whether this is the sort of Mac Pro Apple is going to work on next is debatable, but we can certainly see how it'd appeal to Apple as a company.

Xi3's Piston computer is aimed for gamers. Along with video editors, medical professionals, and 3D designers these are the main audience for such high-end computers. The motherboard of the Xi3 is split into three separate components that are placed in individual boxes and designed to snap together.

Project Piston is designed specifically for gaming and has been optimised for Steam's Big picture mode, so in itself it isn't that interesting to the Mac community. But it's not small project either, Valve has already invested in Xi3.

Mac Pro 2013: Thunderbolt vs PCI Express

What's making this sort of computer possible is the speed increase in external connections.

The current Mac Pro (Mid 2012) is using PCI Express 2.0 which operates at 8GB/s, which is actually slower than the current implementation of Thunderbolt in the iMac and MacBook Air.

Thunderbolt works at 10GB/s.Thunderbolt itself is based on a combination of PCI Express and DisplayPort, so it's capable of not just transferring data, but also connecting graphics cards, monitors and other devices.

As long as they are designed to work with ThunderBolt. The only thing is they aren't, at the moment.

But that doesn't mean it has to stay that way, We can see how Apple could make, build and sell a modular computer made from small cubes that click together using magnets and ThunderBolt.

Whether Apple is interested in such a computer is another matter. It may choose to take the Mac Pro in another route, which integrates some of the technology from the MacBook Air (Flash RAM) and iMac (Fusion Drive) with the PCI Express expandability of the current Mac Pro. Whatever Apple does, we hope it does it in 2013.