Top view of the case

Fanless PC case by Original Twist

A totally silent Mini ITX PC case made from low-cost, off the shelf components with an easy progression from prototype to large scale production.

Things are moving on in the world of desktop computers; they should be cheaper and simpler, but, would you believe it, they’re not. Why?

Main CPUs run much cooler and use less power so, unless you need a powerful gaming rig, you don’t need big fan cooled power supplies or case fans. Heat pipes can remove all the heat most CPUs make.

Solid state discs (SSDs) are cheap and clip neatly into the motherboard M.2 slot. Hard drives are not required at all when data is stored in the cloud.

Delete the SSD and HDD parts on the drawing and what is left? Just a mini -ITX motherboard and (maybe) an open power supply; two components then.  No moving parts, no noise and much less cost.

The Original Twist fanless PC case

The extruded fin case side is glued onto extruded aluminium corner sections; both are available from stock.  The corner sections have slots to accept side panels in any material – the blue parts on this drawing could be marble, for example, or wood.

The huge finned extrusion makes one side of the case.  By huge, I mean really huge. 40mm deep and 160mm wide with a 10mm thick base all ready for embedding 6mm heat pipes. Heat transfer is via 6 heat pipes.

There are multiple disc drive mounting options opposite the motherboard and also higher up the case if required.

The open case power supply (PSU) is mounted low down in the side channel extrusion.  Any heat produced from this and the motherboard drives the updraft.  The case is deliberately like a chimney and needs a bit of heat to get going.

Cooling

Side view

The Magic Power (PSU) in the drawing is only 80W so we’ll probably drop that. A better solution will be a Pico-PSU i.e. an external (sometimes internal) brick with internal ATX distribution leads. The case can easily cool the 65W of the popular Core i5 8400 which will make a very high performance machine at a reasonable price. The 6 heat pipes only use the top half of the case.

When standing up the tall chimney case draws air up through the bottom and expels it at the top so cooling is effected both inside and outside the case. The aluminium corner extrusions are part of the heat sink and are bonded on with heat transfer glue.

The finned  clamp for the heat pipes on the CPU sits neatly in the airflow as do the heat pipes on their path to the side wall. The mother board, mounted at the bottom of the case, heats the air at the lowest point. Full height cock’s-comb RAM coolers also heat the air low down and the same for clip on fins on the SSD.

Case size 124.5 x 240 x 375mm

The components dictate the shape.

Width – the I/O shield between 2 corners

44.5+40+40 = 124.5mm.

Side length – the finned extrusion between 2 corners

160+40+40= 240mm

Height/length – 170mm motherboard with space for HDD above and masses of heat sink

375mm.

Design notes

The corner extrusions come with threaded inserts for the ends and these are used to bolt on the top and bottom plates.

4 big round feet enable the start button to be fitted in the base plate as well as the ‘power on’ LED and an angled power plug.

The radiused corners on the end plates match the case style.

Market position

There are many contenders for this silent PC slot but they are generally expensive and don’t have as big a heat sink. They are computers with heat sinks – ours is more a heat sink with a computer attached.

The beautiful, contrasting black and aluminium finish looks truly modern making this ‘the computer you want’ and in every way better than ‘the computer you need’.  Design flexibility allows the non cooling sides to be in various materials such as wood, aluminium or marble, none of which requires special tooling to produce.

Flexibility

This case provides excellent flexibility for product variation and expansion. The side panel with the I/O plate is long enough to mount DVD players or removable drive bays.

Marketing

Our philosophy is simple. Cut waste and spend the difference on better components.

Designed in solid aluminium this PC brings you beautiful modern looks that reflect the quality and performance of the internals.

To bring you the best value for money with absolute reliability we removed all the moving parts. All discs and fans have been replaced by top quality components to bring you the best value, high performance, totally silent PC.

The solid state drive gives exceptionally fast boot times and application loading.

Super fast USB-3 ports are available for you to plug in your external media storage devices or there is room inside for a hard drive.

The side plate holding the PSU can also house an optical media drive bay (41x146x185mm- dotted line on the drawing). A blue ray player built in makes the perfect HTPC.

The Technical stuff  below … read on if that’s your thing

Assembly

The computer is assembled with the finned side down. The heat pipes are cranked down once clear of the motherboard and are pressed into the machined slots in the side. After that the PSU channel and the opposite face plate are fitted along with the I/O plate.

Any SSDs or HDD are screwed onto the lid with their looms running neatly up the side so as not to impede airflow. This lid and attached corners then bolts on and finally the end plates hold it all together.

The bending of the heat pipes is fairly minimal but it is, none the less, quite critical. The sketch above shows how just 3 shapes of bend are needed to fit all six pipes. The yellow positions show where additional heat pipes could be laid to increase the effective heat sink. The pitch of the heat pipe slots on the heat sink have to be exact multiples of the pitch on the CPU block.

Thermal performance calculations

The 6 heat pipes on the CPU block can remove at least 15W each and almost double that with the case in the upright position. Additional air flow through the case in this position will also remove some 10W from the CPU heat sink. So the pipes can remove well over 100W but, of course, we need to dispose of this heat through the case.

The heat pipes only lie in half of the finned side and the manufacturer’s figures suggest a DegC/W of 0.45 for this length. With the CPU at 50C and a room at 22C we would be looking at 65W cooling power which is in line with the 65W Core i5 8400. Actually CPUs can run much hotter and the cooling power would be equally higher.

The heavy aluminium heat sink side has plenty of room for five additional heat pipes to be placed between the existing ones and with heat pipes embedded along its entire length the case would be able to remove around at least 80W.  It is hoped that the case will be able to lie flat for 55W chips and be good for practically anything while standing up or on a VESA mount. The added cooling power of the corner extrusions has not been taken into account in these calculations so real world performance should be much better than indicated.

Theory is all very well but we can be sure by comparing with several existing silent PCs which work perfectly well. The Original Twist design has cooling surfaces of around 5 times that of the others so this should be the best of its kind. Some PCs have heat sinks; this PC is a heat sink!

This case is not in production yet. If you would like to own this design and the business of producing it please get in touch using the Original Twist contact form.