The use of HBM memory in data center processors shouldn’t surprise us, we already have a few examples like the A64FX from Fujitsu, but this is the first time we see it confirmed in a high performance processor under ISA x86-64.
Keep in mind that this Intel Sapphire Rapids is not the processor you will find in your nearest stores like Rocket Lake and Alder Lake would be, but you have to keep in mind that the technology is generally tested and put implemented first in more experimental and small markets.
Memoria HBM and Intel Sapphire Rapids
In the Chapter 15 of the Intel document titled Programming reference for future extensions and features You can see the table above, which is the processor error codes related to the interface or memory controller, that is, the part of the processor that communicates with the external RAM and in which we can see references to the use of HBM memory.
Given that HBM memory needs to be in operation to be mounted on an interposer in common with the processor, this means that Intel will sell Sapphire Rapids models which will be included in a same packaging What is the CPU and RAM of the system without the possibility of expanding the latter, that is, with a huge bandwidth in comparison, much lower power consumption and taking up much less space.
What is HBM memory?
Memory HBM is a type of RAM It consists of its most extended version of 4 stacked memory chips, which communicate vertically with an interposer, since the communication paths are used through silicon that cross vertically through the different chips. The communication is not done horizontally but vertically, this allows the number of communication pins to be greatly increased and these operate at a lower clock speed and voltage.
Thanks to its characteristics HBM memory he has a much lower consumption when transfer data than conventional DDR memory and its derivatives like GDDR. But its commercial use is limited by the fact that the high production cost of this type of memory is very high, it relegated it to the world of high performance computing or HPC, market in which Intel will obviously launch its Sapphire Rapids with HBM memory.
The usefulness of HBM memory beyond GPUs
We tend to mentally attribute HBM memory as a type of VRAM, the reason is that we have seen it work on AMD and NVIDIA graphics cards, as this memory gives huge bandwidth like GDDR, but it is a memory whose nature makes it ideal for complex multicore systems
But the HBM has a peculiarity and that is that each of the 4 chips in the stack actually has 2 different access channels, these are 8 access channels and therefore we are talking about 8 cores that can access the content. of RAM at the same time. This is the He him equivalent to having 8 DDR4 channels at the same time, but without needing 8 DIMMs to access the memory, which would consume a lot more and take up a lot more space on the board
Taking into account that everything indicates that Intel will add a systolic table, that is, a processor for AI, in Sapphire Rapìds, so it makes perfect sense in the world that there are versions of this processor with HBM memory in order to get the most out of it. performance when performing these types of algorithms.