Compute module 4 questions

[X-Gen]

hi,
Are there any plans for developing a board that will accept multiple modules?

And if yes, could such board share wifi and OS with each module, or should i purchase each module with it's own wifi and ssd?

Because for most compute applications (like boinc), 500MB/core is fine (2GB/module), but if i need to preload the os on each, I'll need at least 2.5GB (+150MB for the OS, and +64MB for the shared vram). 4GB currently being the nearest), would bump up the price considerably from $30 per module, to $55, according to this price list i found online:


For one module a $25 bump is OK,but for any serious parallel computing system, it starts counting with each board (not to mention the cost of any additional boards that could combine or interlink them all).

[cleverca22]

simplest option is to add a gigabit switch (with magnetics for each CM4) so they can all talk to eachother over ethernet

then configure one unit with wifi to act as a router, and do NAT+forwarding+dhcp

[W. H. Heydt]

It's moderately likely that someone will at least try to make a multi-module carrier board. Whether or not you'll be able to find such a thing for sale is another matter. Bear in mind that you would still be clustering multiple Pis and all the usual caveats and cautions apply...mostly that it doesn't become one large system.

[dividuum]

https://turingpi.com/ had an announcement today.

[W. H. Heydt]

https://turingpi.com/ had an announcement today.

Interesting that they say that they "expect" to see 16GB RAM "soon". I wonder if they know something we don't....

[cleverca22]

https://turingpi.com/ had an announcement today.

from over in viewtopic.php?f=98&t=288640

There's lots of companies who had early access to the CM4 for development purposes

i'm guessing that turingpi is one of those companies that had early access to the CM4, only way to explain them having a design out on day 1
even with a giant heatsink that fits the cpu perfectly!

[W. H. Heydt]

https://turingpi.com/ had an announcement today.

from over in viewtopic.php?f=98&t=288640

There's lots of companies who had early access to the CM4 for development purposes

i'm guessing that turingpi is one of those companies that had early access to the CM4, only way to explain them having a design out on day 1
even with a giant heatsink that fits the cpu perfectly!

Least surprising point ever. Another company that almost certainly had had them for some time...NEC.

[Imperf3kt]

https://turingpi.com/ had an announcement today.

Interesting that they say that they "expect" to see 16GB RAM "soon". I wonder if they know something we don't....

I recall hearing one of the engineers state they wanted to add 16GB option should an appropriate RAM package surface.

[W. H. Heydt]

https://turingpi.com/ had an announcement today.

Interesting that they say that they "expect" to see 16GB RAM "soon". I wonder if they know something we don't....

I recall hearing one of the engineers state they wanted to add 16GB option should an appropriate RAM package surface.

I have little doubt that there are people would love that. Does kind of beg the question of what one would use a 16GB Pi4B or CM4 *for* other than bragging rights (MY SBC is bigger than YOURS!). No doubt that they'd sell if they hit the market, though.

[trejan]

Interesting that they say that they "expect" to see 16GB RAM "soon". I wonder if they know something we don't....

I'm not certain they're referring to a Pi. None of the Pi boards or Compute Modules have only had 128MB RAM so they're definitely talking about modules from other manufacturers as well here. The new big feature of the TuringPi 2 being able to take modules from various manufacturers with a module specific adapter also hints at this.

Lets see what happens...

On a side note, I've had photocopied newspaper articles that were better resolution than the TuringPi development sketches. Did somebodies hand slip when using the pencil drawing filter control?

[X-Gen]

https://turingpi.com/ had an announcement today.

Interesting that they say that they "expect" to see 16GB RAM "soon". I wonder if they know something we don't....

They have some nice YouTube introduction videos on the module 3.
I'm comparing it to my own self invented non kubernetes atomic pi cluster, and i'm surprised there are so many similarities in the way we set things up (especially since I had zero training).

As far as a 128GB PI4, ain't gonna happen!
Might be 128GB total ram (16 units of 8GB in one rack...).

One thing I did notice though,
It won't be as pretty anymore, to mount all these boards, because of the plug. It'll kind of need to be mounted horizontally on a motherboard (not vertically, like cm3).
Which means, unless they're working with cables, a CM4 won't plug and play, like a CM3 did.

I'm just surprised there's so much interest in building cluster computers nowadays!

[W. H. Heydt]

https://turingpi.com/ had an announcement today.

Interesting that they say that they "expect" to see 16GB RAM "soon". I wonder if they know something we don't....

They have some nice YouTube introduction videos on the module 3.
I'm comparing it to my own self invented non kubernetes atomic pi cluster, and i'm surprised there are so many similarities in the way we set things up (especially since I had zero training).

As far as a 128GB PI4, ain't gonna happen!
Might be 128GB total ram (16 units of 8GB in one rack...).

Per CM4, no. The external addressing limit for the BCM2711 is 16GB.

One thing I did notice though,
It won't be as pretty anymore, to mount all these boards, because of the plug. It'll kind of need to be mounted horizontally on a motherboard (not vertically, like cm3).
Which means, unless they're working with cables, a CM4 won't plug and play, like a CM3 did.

The Turing folks have a solution to that. They're planning to mount the CM4s to, basically, riser cards that then plug vertically into a common ITX sized board.

I'm just surprised there's so much interest in building cluster computers nowadays!

There has always been interest in clustering Pis. One of the very first Pi projects that got written was a cluster of Model B Pis with a LEGO "case" to hold them.

The problem is that a lot of people get the weird idea that you can "cluster" Pis to either make an actual supercomputer, or that you can somehow make the cluster look like a single, much more powerful system. What I usually do is ask such people if they think they could do that with a bunch of PCs, and if they don't think that would work, why would they expect it to work with Pis?

[X-Gen]

I think that would be the ultimate thing!
To combine like a bunch of Pis (quadcores) to appear like a single unit.
To make that work, you'd kind of need a central CPU (eg: a quadcore) with at least 4 pcie lanes, and rout one lane to a quadcore Pi unit..

What I'm actually here for, is that industrially the 'smarc' connectors is what companies are using nowadays. They look like SoDimm modules, and kind of what CM3 modules look like.
The CM4 is departing from that.
While it won't matter much for a motherboard hosting these modules, as they're just the same lanes on a different plug, the negative side of it all is stacking.
Yes, one can have a horizontal motherboard with vertical extensions, but they're never going to be as good as when using a sodimm slot.
One could stack 2 of these units on each side of a vertical extension, but that would only lower the cooling efficiency (vs having the CM3 modules installed, as each CM4 module is now back to back, with a heat insulator (fiberglass board)separating them from one another).

I actually can't think of any benefit of using the new connector.
They say 'boards can now be lower in profile thickness', but that's a lie.
With CM3 modules, one could build a motherboard around the CM module if one wanted.
With CM4 modules, there always will be the module with an additional motherboard or fiberglass extension board sandwiched together. And those 2 are definitely not thinner than the sodimm socket of a CM3 module.

[W. H. Heydt]

I'm not at all sure that you have grasped the target markets of either the "main line" Pis, nor of the CMs.

[X-Gen]

I'm not at all sure that you have grasped the target markets of either the "main line" Pis, nor of the CMs.

CM = COMPUTE MODULE.
In other words, used for COMPUTE!
It'd only be logical to have a system running many of these.

[jamesh]

I'm not at all sure that you have grasped the target markets of either the "main line" Pis, nor of the CMs.

CM = COMPUTE MODULE.
In other words, used for COMPUTE!
It'd only be logical to have a system running many of these.

Completely wrong.

A single instance of a product could have one of these in it. e.g. The 5-Ninja's slice.

That is by far the biggest use case.

Of course, you could make a base board that took more than one if you wanted.

[X-Gen]

I'm not at all sure that you have grasped the target markets of either the "main line" Pis, nor of the CMs.

CM = COMPUTE MODULE.
In other words, used for COMPUTE!
It'd only be logical to have a system running many of these.

Completely wrong.

A single instance of a product could have one of these in it. e.g. The 5-Ninja's slice.

That is by far the biggest use case.

Of course, you could make a base board that took more than one if you wanted.

Tell me then, what other purpose does a COMPUTE MODULE have, than to COMPUTE?
You say I'm completely wrong, but I think these modules' main purpose is to do computations.
There's little use for single units doing computations, as that's no difference than a Pi board.
I think the main goal for CM modules, is to stack em (cluster).

[dickon]

[Tell me then, what other purpose does a COMPUTE MODULE have, than to COMPUTE?
You say I'm completely wrong, but I think these modules' main purpose is to do computations.
There's little use for single units doing computations, as that's no difference than a Pi board.
I think the main goal for CM modules, is to stack em (cluster).

It's as a System-onna-Module for industrial control / embedded display / etc. applications. It isn't any better at clustering than any other Pi.

[jamesh]

CM = COMPUTE MODULE.
In other words, used for COMPUTE!
It'd only be logical to have a system running many of these.

Completely wrong.

A single instance of a product could have one of these in it. e.g. The 5-Ninja's slice.

That is by far the biggest use case.

Of course, you could make a base board that took more than one if you wanted.

Tell me then, what other purpose does a COMPUTE MODULE have, than to COMPUTE?
You say I'm completely wrong, but I think these modules' main purpose is to do computations.
There's little use for single units doing computations, as that's no difference than a Pi board.
I think the main goal for CM modules, is to stack em (cluster).

All computers compute. That doesn't mean all computers need to be clustered.

The majority use case for CM's is as ONE device embedded in another device - for example, the Slice, or in the back of a NEC TV, or in a kiosk. You could use a normal Pi, but the CM gives you a more customisable solution.

[W. H. Heydt]

I think that would be the ultimate thing!
To combine like a bunch of Pis (quadcores) to appear like a single unit.
To make that work, you'd kind of need a central CPU (eg: a quadcore) with at least 4 pcie lanes, and rout one lane to a quadcore Pi unit..

Do you think that would work with a bunch of standard PCs? If not, why would think it would work with a bunch of Pis, or CMs?

[jamesh]

I actually can't think of any benefit of using the new connector.
They say 'boards can now be lower in profile thickness', but that's a lie.
With CM3 modules, one could build a motherboard around the CM module if one wanted.
With CM4 modules, there always will be the module with an additional motherboard or fiberglass extension board sandwiched together. And those 2 are definitely not thinner than the sodimm socket of a CM3 module.

There are many benefits. More robust, more lines, easier board layout, cheaper boards, lower height (yes, not a lie at all!). When this was shown to resellers a half a year ago, they were delighted with the form factor change. Much more in keeping with their industrial customers requirements.

[X-Gen]

I actually can't think of any benefit of using the new connector.
They say 'boards can now be lower in profile thickness', but that's a lie.
With CM3 modules, one could build a motherboard around the CM module if one wanted.
With CM4 modules, there always will be the module with an additional motherboard or fiberglass extension board sandwiched together. And those 2 are definitely not thinner than the sodimm socket of a CM3 module.

There are many benefits. More robust, more lines, easier board layout, cheaper boards, lower height (yes, not a lie at all!). When this was shown to resellers a half a year ago, they were delighted with the form factor change. Much more in keeping with their industrial customers requirements.

No, the height can never be as thin with this new design, compared to the CM3 design.
Not that it matters though, as they're mostly mounted vertically (on a horizontal motherboard) for multi units.
But like I said, the CM3 module in (retro) gaming consoles, have a Sodimm slot the CM3 fits in. The rest of the motherboard is built around the CM3 module.
Not possible with CM4, so it's not possible for it to be thinner.
Yes, if the motherboard is built underneath a CM3 module (like most RAM slots in a laptop) it might take up more space.
But if thin-ness is an issue, the CM3 units can actually go thinner than the CM4 units (I know this, without ever needing to have seen one in person), due to the fact that the CM3 modules can be mounted not just parallel, but on the same plane as a motherboard.

I remember seeing 2 designs, one which had a cutout where the CM3 module would fit in (motherboard is built around the CM3 module, O-shaped),
And the other one was just a CM3 module in a sodimm slot, with 2 separate boards on each side (motherboard U-shaped).

[cleverca22]

But if thin-ness is an issue, the CM3 units can actually go thinner than the CM4 units (I know this, without ever needing to have seen one in person), due to the fact that the CM3 modules can be mounted not just parallel, but on the same plane as a motherboard.

where did you find such a connector?
viewtopic.php?f=98&t=285821 was asking about one, but i dont think they ever found it

[X-Gen]

But if thin-ness is an issue, the CM3 units can actually go thinner than the CM4 units (I know this, without ever needing to have seen one in person), due to the fact that the CM3 modules can be mounted not just parallel, but on the same plane as a motherboard.

where did you find such a connector?
viewtopic.php?f=98&t=285821 was asking about one, but i dont think they ever found it

Sorry, I edited the post, as this one wasn't the right image and still uses a standard SoDimm connector. You just don't notice the black motherboard behind it.
I don't have one, but remember seeing one (a good 2 years ago) on a site that sold retro handhelds.

Would this work?
https://www.digikey.com/en/products/det ... LF/1001323

Instead of soldering the slot the regular way, you can solder it upside down (connectors being soldered on the back side instead of on top of the board), allowing the unit to be flush with the board:

[trejan]

No, the height can never be as thin with this new design, compared to the CM3 design.

Okay.

CM4: "The Module is 4.7mm deep, but when connected the height will be 5.078 or 6.578 mm depending on the stacking height chosen"

CM3: SODIMM socket is 5.2mm by itself and the CM3+ SoC will protrude slightly as well because of the heatspreader.