I feel like I can help levitate some of the confusion over the RAM used in the Xbox Series X.
Lets start with the RAM type used in the Xbox series X, GDDR6 memory is usually reserved for graphics cards, which typically benefit from the very high bandwidth found in this RAM. In case of the Xbox it’s 2 types of bandwidth, one with 560 GB/s and one with 336 GB/s. We have 10 Gigabytes of the faster type RAM and 6 Gigabytes of the slower type. The amount of RAM useable by game developers is 13.5 Gigabytes with 2.5 Gigabytes being reserved for the OS and background applications. It’s a unified memory pool, which developers can allocate the required amounts of RAM freely to either the CPU or the GPU.
Now onto the problems:
A lot of people seem to think there a two major problems with the RAM. The first one being “there is slower 336 GB/s RAM in there, is that really enough ? Why was that build in ?“, this is not really a issue in game development in fact in won’t even matter. The reason being, that the 3.5 Gigabytes of RAM that is being available of this slower RAM will be used for the CPU. Processors do not really need this insane amount of bandwidth and don’t really benefit from this, which is why pc‘s use DDR4 memory for the cpu, which if compared to GDDR6 even the slower type lakes a lot in bandwidth. The CPU benefits much more from lower latency and is a key factor in RAM for communication between the two. Also we need to take into account that the CPU usually in games needs more RAM then the GPU, but this of course heavily depends on the Game. So assuming we need 6 Gigabytes of RAM for the GPU at all times which is a really high number in the console area, we still would be left with 7.5 gigabytes of RAM for the CPU at all times, of which 3.5 gigabytes is of the slower bandwidth type. So the bandwidth is not really a issue for game development. And please remember that the amount of RAM needed to either cpu or gpu is allocated by the game developers depending on their needs.
Now for the second problem “Is 13.5 Gigabytes really enough for the next gen?“, now this is a much more complex issue, which I guess we will see over the next years, though from my standpoint at least for now it’s plenty. With the next generation consoles we will be benefitting a lot from new technologies, and one major factor will be the ssd. The new storage medium will allow us to cache much less things in the RAM and rely much more on simply pulling things off the ssd. Also keep in mind that memory allocation will be much more efficient this generation, more on that will be revealed down the line (or not as that is usually only really interesting for developers). So with taking this into account, do I think it’s going to be enough for the next generation ? Yes I do, people will see that this generation will allow for a much better memory efficiency and it will show with the true next gen games.
I really hope this helps some of you.