Turing Pi 2 mini-ITX cluster board takes four Raspberry Pi Compute Modules 4

Can you remember Turing Pi mini-ITX cluster board taking up to 7 Raspberry Pi Compute Modules launched last year? Honestly, I had forgotten about it until I was asked this morning is Gumstix CM4 to CM3 adapter could be used to replace Compute Modules 3 with Compute Modules 4 in the cluster board.

When I went to Turing Pi website to have a look at the board, I discovered the company had made an announcement about Turing Pi 2 cluster board specifically designed to take up to four Raspberry Pi CM4 modules.

We only have the layout for the cluster board because it’s still under development. Since board-to-board connectors – as found in Raspberry Pi Computer Module 4 – are not ideal for density, the company went with a design including 260-pin SO-DIMM connectors plus CM4 adapter boards. But more on that a little later.

Turing Pi 2 preliminary specifications:

  • SoM interface – 4x 260-pin SO-DIMM slot for up to four Raspberry Pi CM4 modules for a total of up to 16 Cortex-A72 cores, 32GB RAM, 128GB flash storage
  • Storage – 2x SATA III ports via a PCIe controller connected to one CM4 module
  • Video Output – 1x HDMI port, 1x MIPI DSI header
  • Audio – 3.5mm audio jack, digital audio via HDMI
  • Network connectivity
    • 2x  Gigabit Ethernet RJ45 ports
    • Layer-2 managed switch with VLAN support
  • USB – 4x USB ports, USB header
  • Expansion
    • 2x mPCIe sockets, each connected to a specific RPi CM4 module
    • I2C header for cluster management
  • Misc – fan header and 40-pin GPIO header for each Raspberry Pi Compute Module 4, RTC + coincell battery holder
  • Power Supply – ATX header
  • Dimensions – 170 x 170 mm (Mini-ITX form factor)

There are some positive developments with support for mPCIe ports and dual SATA via a PCIe to SATA controller, but the number supported modules decreased from 7 to 4. They wanted to keep the costs in check, and the photo below may also explain it…

Each module will be quite thicker because of the need to stack the Raspberry Pi CM4 module on a 260-pin module, and the thick heatsink required to keep the quad-core Cortex-A72 processor cool.

Some of the use cases for Turing Pi 2 include edge infrastructure for self-hosted applications & services, designing an Arm Workstation for developers, building images for AWS instances for Amazon Graviton 1/2 processors, Kubernetes, etc…

The Turing Pi 2 cluster board is expected to launch next year, with the company expected it to be cheaper to manufacture, and offering a 25% discount to existing Turing Pi v1 customers.

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willy
willy
1 month ago

Given the added complexity required to reach a high density with this board, I doubt it will be really affordable to make clusters out of it. For $750 you can have a readily usable HonneyComb LX2K with 16 cores at 2 GHz, M2, 4xSATA, PCIe 8x, 4×10 GbE, and all that under a single system image. That’s a lot better than the 4×4 cores and 2x1GbE proposed above, which I’m not sure will be significantly cheaper. The big challenge with the Pi4 is the cooling of a 28nm chip, which is not very compatible with high density computing anymore. At… Read more »

Theguyuk
Theguyuk
1 month ago

Needs someone to make S905X3, S905X4 and S922X som.

Failing that Friendlyelecs RK3399V2 compute modules. Just need a cluster board.

willy
willy
1 month ago

It’s not interesting to make compute modules based on A53/A55 cores. However for S922X (or A311D) why not, this would offer 4xA73 per module, which is pretty nice. The RK3399 isn’t that great for computing. Half of its power is on the 4 low-performance cores which are hardly usable for anything, and no single core alone can max out the DRAM bandwidth. In that regard the S922X is way more balanced. The real strength of the RK3399 is its connectivity. It’s one of the only affordable ARMv8 chips with GbE+USB3+PCIe. With most others you have to sacrify at least one.… Read more »

Theguyuk
Theguyuk
1 month ago

Cheers for the explanation.

If you have big pockets I found firefly Cluster Server R1 $2000.0. Supporting up to 11pcs RK3399 six-core 64-bit core board, with 1.8GHz processor performance of up to 66 cores.

Chris Daniels
Chris Daniels
1 month ago

I’m totally just a RaspPi hobbyist, but at I’m looking at the older: “$25 for the RPi CM3 Lite modules: a 7-module system would go for a little over $300, not including microSD cards nor a power supply” Frankly, I have no idea of the relative plusses or minuses of Pi other than $. But I’m guessing for needs much beyond the “Turing 1”, you should look somewhere else for clustering ARM boards.

Scott Lamb
1 month ago

Re: RK3399 NAS, that sounds like the Helios64. It has 5 SATA ports via a 2-lane controller. Also 1 GbE + 2.5 GbE Ethernet, the latter over USB3.1. I’m unsure where the other 2 PCIe lanes go; maybe to the USB controller?

tkaiser
tkaiser
1 month ago

> I’m unsure where the other 2 PCIe lanes go

Nowhere. RK3399 has a x4 implementation and since no PCIe switch/multiplexer is used on Helios64 those two lanes have no use at all: https://www.cnx-software.com/2020/01/03/kobol-helios64-rk3399k-sbc-5-bay-nas-pre-orders-to-start-next-week/#comment-569822

Arnd Bergmann
Arnd Bergmann
1 month ago

I agree there isn’t much point in a cluster of devices like these if the goal is to do things cheaper than on larger single-system-image machines, and all the advertised use cases seem a bit questionable. However, I do see use cases in which it does make sense: Building a continuous-integration system for software that is already Raspberry Pi specific and would not run on other SoCs but needs a better form factor than individual SBCs. Teaching about HPC clustering without the budget to pay for HPC hardware. Clearly the performance trade-offs are different, but you can still learn about… Read more »

NicoD
NicoD
1 month ago

I’m no huge RPi4 fan(nor heatsink). But having 4 modules at once should be great.
The BCM2711 isn’t the best for this goal. A lot of heat and high power consumption for the performance. Well, my pc does it worse…
More modules would have been better too. But I bet it’s going to make someone happy.
I can dream of it tonight. Pay it I will not.

Anonymous
Anonymous
1 month ago

Nah, we should have big, high core count ARM chips that can go on to mini-ITX motherboards. Using multiple 8-core DynamIQ clusters of Cortex X1/A78/A55, or Neoverse.

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