Tuesday, April 26th 2022
Dell's DDR5 CAMM Appears in More Detail, Comes in Several Shapes, Won't be Proprietary
Last week the first details of Dell's CAMM (Compression Attached Memory Module) made an early appearance courtesy of a product leak, but now official details have appeared and the good news is that Dell is saying it won't be a proprietary solution. The Compression Connector looks unlike anything used by consumer computers today and Dell is said to be hoping that it'll be the next industry standard for memory modules, according to PCWorld. The interposer mentioned in the previous news article is also mentioned and allows for a pair of DDR5 SO-DIMMs to be used, albeit with a much taller Z-height.
Dell is apparently planning on getting its CAMM approved by the JEDEC, which is the standards organisation when it comes to memory. However, even if the CAMM format is accepted as a JEDEC standard, Dell holds patents and is likely to charge some kind of royalty fees to interested parties. That said, if it becomes a JEDEC standard, Dell has to follow RAND or Reasonable and Non-Discretionary terms, so the royalty fees would have to be reasonable for JEDEC to agree on making CAMM a standard. The main benefit of Dell's CAMM is that the memory traces end up being shorter and more direct, since the CAMM has a single-sided interface, whereas SO-DIMMs are interfaced on both sides, just like standard DIMMs. This would allow for higher speed memory interfaces, without the need of using something like signal re-drivers or re-timers.
Dell is apparently getting ready for DDR6 already and told PCWorld that by the time DDR6 arrives, SO-DIMMs are no longer going to be fit for purpose. Another advantage of the CAMM, is that higher memory speeds can be used in combination with greater densities of RAM, as a single CAMM can host 128 GB of DDR5. The type of connector used is known as DGFF and Dell is already using it in some of its products today, as a bridge connector for GPU boards among other things. Dell claims that the DGFF connector is capable of handling frequencies of up to 20 GHz, or four times the speed of DDR5 memory at 4800 MHz. The physical CAMM will come in different shapes and sizes, but the common part is the compression connector, which is as the name implies, compressed in place with the help of a pair of screws. Additional screws are also used to hold the CAMM securely in place, with the modules shown, using between four to six screws in total.
Dell also claims that the CAMM connector can act as a heatsink and help with heat dissipation, although the company didn't go into any details of exactly how this is meant to work. There will be what Dell calls a bolster plate that sits above the CAMM, most likely to protect it from damage from the screws, but it seems like it could also be extended as part of a heatsink if needed. The bottom bolster is what the top bolster screws into, rather than the compression connector itself. It should be noted that the CAMM doesn't have any kind of pins, so precision installation is going to be key, but judging from the pictures provided there are some kind of guides to make this easier. Each of the 14 interface rows appears to have 44 contacts per, for a total of up to 616 interface contact points. The contact points seem to vary in shape and size depending on their function. A CAMM can be single or double-sided, depending on memory density and Dell has developed CAMM's ranging from 16 to 128 GB. Dell will start shipping computers with CAMMs installed later this quarter.
Sources:
PCWorld, VideoCardz
Dell is apparently planning on getting its CAMM approved by the JEDEC, which is the standards organisation when it comes to memory. However, even if the CAMM format is accepted as a JEDEC standard, Dell holds patents and is likely to charge some kind of royalty fees to interested parties. That said, if it becomes a JEDEC standard, Dell has to follow RAND or Reasonable and Non-Discretionary terms, so the royalty fees would have to be reasonable for JEDEC to agree on making CAMM a standard. The main benefit of Dell's CAMM is that the memory traces end up being shorter and more direct, since the CAMM has a single-sided interface, whereas SO-DIMMs are interfaced on both sides, just like standard DIMMs. This would allow for higher speed memory interfaces, without the need of using something like signal re-drivers or re-timers.
Dell also claims that the CAMM connector can act as a heatsink and help with heat dissipation, although the company didn't go into any details of exactly how this is meant to work. There will be what Dell calls a bolster plate that sits above the CAMM, most likely to protect it from damage from the screws, but it seems like it could also be extended as part of a heatsink if needed. The bottom bolster is what the top bolster screws into, rather than the compression connector itself. It should be noted that the CAMM doesn't have any kind of pins, so precision installation is going to be key, but judging from the pictures provided there are some kind of guides to make this easier. Each of the 14 interface rows appears to have 44 contacts per, for a total of up to 616 interface contact points. The contact points seem to vary in shape and size depending on their function. A CAMM can be single or double-sided, depending on memory density and Dell has developed CAMM's ranging from 16 to 128 GB. Dell will start shipping computers with CAMMs installed later this quarter.
37 Comments on Dell's DDR5 CAMM Appears in More Detail, Comes in Several Shapes, Won't be Proprietary
This is the current bridge connectors that Dell is already using in some of their products, but in multiple sets to connect graphics cards.
Below that is a card with three sets of pads, which is what the CAMMs will have. Note that the graphics card was made in 2018, so this is not something new for Dell.
It's not nearly as complex or as easily damaged as LGA sockets.
And that's part of the thing: that being a 15" device inherently makes it easier to make it thin, through allowing for the use of wider, lower profile components (chokes, batteries, fans, etc.). That yours seems to use its SO-DIMMs as a structural component just supports this - apparently there's zero clearance there! So, for example, a thinner memory module could then allow for a better supported bottom plate design with more rigidity. Or it could allow for a larger battery than that relatively paltry 51Wh unit. Or it could allow for the second fan to be the same size as the first.
(Also, it's rather odd for you to seemingly use the structural support offered by the DIMMs as some kind of pro here - that's clearly a poor casing design, neither more nor less, and using a more space efficient memory type wouldn't affect that in either direction. That the laptop does overall seem to have some very odd priorities made in its design - such as that tiny secondary fan - speaks more to a poor overall design than this somehow being related to its use of SO-DIMMs. Also, it's often cheaper to stick a pair of SO-DIMM slots on a board than to design trace routing for a soldered memory layout. Off-the-shelf, high volume components are very cheap.)
(You're also misrepresenting some things a bit here: your battery is stacked with the touchpad, so it's only partially full thickness, and the speakers live in the tapered portion of the chassis, mostly being far thinner than the middle. The chassis also seems to have an overall wedge shape, being slightly thinner at the front, but that might just be an optical illusion from the tapered front edges. But regardless of this, both batteries and speakers can be shaped quite freely to fit whatever space is available. SO-DIMMs can't.)
Heck, you have 13" devices with SO-DIMMs too, like the Framework laptop, but in that you can again see just how ludicrous the board space requirement for dual SO-DIMMs is for such a small device. (And it's greatly helped by using a 3:2 display, giving it just that tad extra area to work with.) That doesn't mean it can't be done, but it comes with severe drawbacks, and it has a strong deterministic effect on the possible design variations. A more spatially efficient design will change those effects, giving more design flexibility.
After all, as that CAMM-to-SO-DIMM carrier board shows us, the CAMMs are barely wider than a SO-DIMM, yet they are inherently dual channel - and they don't need to be as deep (long?) as the full sized designs. Unless you're designing for a memory capacity of 64GB or more (which isn't necessary for the vast majority of consumer products), you can design for the smallest CAMM size, which is barely larger than a single SO-DIMM in X and Y, while being lower in Z.
Just to be clear (which IMO I have been, but apparently repetition is still needed): I have in no way argued for the creation of thinner laptops. I've argued that this can allow for more densely packed devices with more efficient internal layouts without sacrificing repairability and upgradeability. SO-DIMMs due to their size and Z-height have a strong determining effect on where they can be placed and how they fit, and even if they hang off a motherboard edge they require a lot of vertical clearance to fit as they're nowhere near in line with the motherboard. Doing the same with this CAMM would be far more spatially efficient, and allows for more flexible implementations overall. You can still make the design thicker if you want to, and if you do, you have more space for structural support, larger batteries, larger (or more) speakers, better keyboards, etc. Or you can go thin without needing to resort to soldered memory. This can allow for less compromised designs. And that's the important part. Sure, it can also be used for ludicrously thin, bad designs - but if that's the way an OEM wants to go, they can already do that with soldered RAM. There are no new disadvantages to this design outside of possibly cost and the time needed for standardization and adoption. But there are also plenty of advantages - OEMs just need to make use of them.
Here's another example: my work laptop, a Dell Latitude 7390 2-in-1. It's a pretty bad laptop in many regards, with poor cooling and a CPU configured to a mere 12W. It also has the smallest, thinnest fan I've ever seen (and it still vibrates and touches the casing at times!). Most of this is likely because Dell chose to give this laptop a pretty great keyboard (for its thickness), plus (like with yours) a thick, reinforced display for pen input.
Still, I'd like you to let me know how they could have fit upgradeable memory in here with SO-DIMMs. Because judging by the size of these CAMMs, they could have fit the smallest size of CAMM in here, under the RF shield where its soldered memory lives. (It's also worth noting that the Latitude has a bigger battery than your 15" device!). So: tradeoffs have been made. This is still not a very thin device, mostly thanks to the very thick display. But it's fine in terms of size. If CAMM could allow for designs like this (or ideally better executed ones) with upgradeable memory, that would be amazing.I really, really wish something like this could be adopted as an industry standard. That would be so great, on so many levels.
Also, my old 12.5" Thinkpad X250 has a SO-DIMM slot and it has two batteries as well...
Personally I still think we need to move to a better interface, if this is it or not, I don't know. However, at some point in time, progress is needed.
I have no problem with SODIMMs being universally superseded by something faster, but if CAMMs fragment the DDR6 market into conflicting standards, that's a terrible thing.