Prototype Project Orthrus - Smallest SLI mATX case (V2)


Master of Cramming
Original poster
Case Designer
Jun 29, 2016


Over the past 18 months or so, I've been working on a project and it's aim was to create a quiet, extremely powerful and compact computer. Something that can live on a desk as well as a home theatre cabinet.
Typically, when talking about PC's, those three adjectives can't really be used together, as powerful PC's usually draw a lot of power and exert a lot of heat, therefore need a lot of cooling, which is usually loud. This is how project Orthrus was born.

Project Name:

The name, which is only a working title for now, stems from Greek mythology. Its a symbol for a two headed guard dog (symbolizing the use of dual GPU's). Coincidentally enough, Orthrus was Cerberus' brother :) (My shout out to Kimera Industries guys here)

Principal of the design:

As mentioned previously, high performance computer parts and compact enclosures usually don't go well together. That is unless you move the components in the case around in a way which allows all of them to draw fresh cold air from the outside of the case.
Putting the dual GPU's straight on the back of the motherboard, not only allows the two GPU's and the CPU to breathe their own air, but allows to minimize the width of the chassis, by putting the only 2 perfectly flat parts of the PCB's against each other.

To achieve this, a number of design decisions were made:
- PCIe risers had to be used to place the graphics cards on the opposite side of the case.
- Longer than usual SLI cables had to be used to join the graphics cards together
- Only 2,5" disks would be used (when using both GPU slots), as 3,5" disks are too big, and with the cost of 1TB SATA SSD's quite low these days, I didn't see a point.

Case Details (V5):

Height: 33.60 cm
Length: 34.50 cm
Width: 13.40 cm
Weight: TBD
Volume: < 15.5 Litres
Material: 3mm Aluminium
Side Panels: 3mm Aluminium or 3mm Acrylic
Front Panel I/O:
- 3 x Keystone jack for keystone modules (including HDMI for VR Ready)
- 1 x Power Capacitative Button
Orientation: Horizontal or Vertical
PCIe Riser 1: Li-Heat Next Generation (350mm)
PCIe Riser 2: Li-Heat Next Generation (400mm)

Compatibility of components:

Intel: 1151 / 2011 / 2011-3 / 2066
AMD: AM3 / AM4

CPU Coolers (up to 53mm - verified):
Noctua NH L9i (Recommended)
Thermaltake Gravity i1
Akasa K25
Silverstone AR05
ID Cooling IS-VC45 (will be compatible with v2)

mATX and ITX

Dual GPU's supported
- Length: Up to 295 mm
- Height: Up to 112 mm (measured from PCIe connector to top of card)
- Up to 250 Watt TDP (due to PSU restrictions)

Any memory up to 53mm in height will fit.

FlexATX (up to 250mm length)
1U PSU (up to 250mm length)

Recommended PSU's:

For Single GPU builds: Modular:
Seasonic SS500L1U (500W - Gold)
For Dual GPU builds: Non-Modular:
FSP FSP700-80UEPB (700W - Platinum)

For Single GPU builds:
FSP500-50FSPT (500W - Platinum)
For Dual GPU builds: Non-Modular:
FSP750-50FGGH1 (750W - Gold)
FSP850-50FGGH1 (850W - Gold)



Motherboard side: 2 x 2,5" disk
GPU side: Replacing the 2nd GPU: 1 x 3,5" disk + 1 x 2,5" disk
Top of case: 3 x 2,5" disk

240mm Radiators up to 124mm wide, up to 278mm tall.
Thickness of the radiator + fan should not exceed 58mm
CPU Waterblock/pump height limitation is up to ~53mm
GPU Waterblock support:
- Full reference card waterblocks like EK and Bitspower are supported (for top GPU slot)
- If doing DUAL GPU water cooling, for bottom GPU slot, a universal GPU cooler like the EK-VGA Supremacy or Koolance GPU-220 / GPU-230 is supported.

2 x 120x120 mm (thickness depends on radiator size used)

Benchmarks - Noise / Power Consumption / Temperature:

Photos (Case Only):

Photos (Custom waterloop build):

Coming soon ...

Preview by Linus:

Last edited:


Standards Guru
Sep 3, 2015
Oh 1U PSU? Good choice, I had seen the PSU slot and thought it was Flex ATX which have limited offerings on higher wattages


Efficiency Noob
Jun 19, 2016
Wow absolute baller! Mad props for the case detail breaking up the monotonous fan grill, looks very professional.
Madness that you fit a mATX with dual gpu in that form factor. Interesting method of using slotted aluminium tabs for the side panel mounts.


Lord of the Boards
Editorial Staff
Gold Supporter
May 9, 2015
Welcome ! Glad you posted your project, many people here are enthusiastic about it !
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Zeroth Alpha

Cable Smoosher
Jul 24, 2016
Absolutely excited to see what becomes of your project! I have an immense appreciation for things that use creative engineering to overcome the constraints of old standards.


Airflow Optimizer
Sep 9, 2015
Hey Luke, just noticed you are using the Noctua NH-L9i, but swapped the 92mm fan for a Scythe 100mm fan.

Did you have to drill hole into the fan to fit the mount on the heatsink? Or is it plug and play?

Edit: Nvm, found out it has both 92mm and 100mm mount holes. Nice!
Last edited:

CC Ricers

Shrink Ray Wielder
Bronze Supporter
Nov 1, 2015
Nice to see this project on here. Not just a great case but also a well-executed build around it.


Spatial Philosopher
Apr 1, 2016
That's a truly inresting project! Dual gpu show off!

Size is good and the two gpu are not bothering each others!

One small question however : why not going to external SFX power supply instead of 1U psu that could be truly noisy especially with multi gpu setup?? Look at my NFC S4 mini can even consider smaller case..:)

For me it's ideal to receive xfire of RX 480..:)


Master of Cramming
Original poster
Case Designer
Jun 29, 2016
Guys thank you so much for the kind words. I've been a long time reader / lurker of the forums, so it finally feels great to be able to contribute something and see such a positive response.

Happy to answer any questions, I'll be on here regularly. If you also like to follow me on twitter @LukeD_NC
I'm new to twitter so please be nice :) especially if i at you, or hash tag incorrectly ;)

With regards to using 1U PSU, provided you use a good quality one, like the one I'm using from FSP (700 Watt Platinum) it doesn't even break a sweat. Hopefully this weekend I'll make a video of the power supply / noise for all of you to judge. Hopefully that will put a lot of the worries to rest.

Also, using dual 1080's in this setup with 6700k i found i don't get more than 420 watts from the wall at 100% stress test (both cpu + gpu).
So the power supply barely warms up.


Master of Cramming
Original poster
Case Designer
Jun 29, 2016
Also, I ask if anyone has any questions they'd like to shoot my way, please do.
Especially if its with regards to the case and its functionality.
I'm reaching out to the community because I've built a case which by most part fits my needs and wants and I would like to incorporate yours into the design (if possible) before a 2nd prototype is made and hopefully after that a first batch.


Spatial Philosopher
Apr 1, 2016
I must admit your design even make me wonder to come back to crossfire (of rx 480 right now...thus no issue of sli cables..:))

I've some questions :
  • Do you undervolt your cpu to reach these temperature? On core i7 6700k you are reaching 68°c, same range as my core i7 6700k undervolted in unclosed case?
  • What is your expected price? What will be shipping cost for europe (france for me) or usa?
  • You have used a nicely modded server 1u..however not everybody could do it.:) is there any way to consider internal modular sfx? As plan b, I'm fan of external sfx psu (see my signature on nfc s4 mini..;))
  • Let's suppose we chosing to go for mini itx config, is it feasible to put a very tall gpu like msi gtx 1080 gaming x? Also on mini itx, how do you cool m.2 on backplate of motherboard?
  • Is it possible to go for smoky side panel? I guess you put vents holes following your needs. Could you adjust or customize it to specific vents or design?


Master of Cramming
Original poster
Case Designer
Jun 29, 2016
Hi guys, sorry I've been away from the forums due to a family emergency.

Marc to answer your questions:

- I don't undervolt the 6700k. I run it on auto-volt settings on the ASUS Maximus VIII Gene.
- I think I will have at least 2 SKU's: 1 with psu + 2 riser cables, the other without PSU's or risers.
The version with 700 Watt platinum PSU + 2 risers I think will be around $550-600 USD
The version without PSU or risers will be around $250-300 USD.
These are very rough estimates and are likely to change. I'm yet to shop around for manufacturers that could produce this.
- SFX size PSU's will not work however version 2 of the design will support both 1U server and FlexATX. (you could use an external psu - depending on your motherboard)
- Yes, it is possible to put very tall GPU's if only 1 is going in.
- The cooling of m.2 (in my motherboard - because its between PCIe slots occurs) due to front fan air flow. If you have a motherboard with m.2 on the back you can use silicon heat transfer pads and use the middle mounting aluminium tray to transfer the heat.
- Yes, smokey side panel is possible. I will be evaluating panel options once i have revision 2 design made.
- I am going to evalutate if panels will come perforated or not (for improved air flow)
- You cannot fit a 360 radiator as the case is thinner than a 360 radiator - which is 120mm wide.
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Spatial Philosopher
Apr 1, 2016
I hope your family emergency is not that bad..:(

Thank you for yours answers, it's truly an exceptionnal case, both in technical specs and price...:)
In sales option #1, case with risers and psu, does is include cable mod and psu painting?...:)


Jessica. Wayward SFF.n Founder
Gold Supporter
Feb 22, 2015
The version with 700 Watt platinum PSU + 2 risers I think will be around $550-600 USD
The version without PSU or risers will be around $250-300 USD.
These are very rough estimates and are likely to change. I'm yet to shop around for manufacturers that could produce this.

Speaking from experience, I would highly recommend finding a manufacturer and working through all the costs before you start quoting prices to people.

Prices are highly dependent on quantity, so assume only 10-20% of the people that express interest (on forums, reddit, signed up for the newsletter, respond to surveys, etc.) will actually follow through with their wallet.