Quad-channel RAM is common on consumer desktops. Strix Halo has *8* channels, and also very fast RAM (soldered RAM can be faster than dimms because the traces are shorter.)
Quad channel memory is not common on consumer desktops, it's a strictly HEDT and above feature. The vast majority of consumer desktops have 2 channels or fewer.
One should no longer use the word "channel" because the width of a channel differs between various kinds of memories, even among those that can be used with the same CPU (e.g. between DDR and LPDDR or between DDR4 and DDR5).
For instance, now the majority of desktops with DDR5 have 4 channels, not 2 channels, but the channels are narrower, so the width of the memory interface is the same as before.
To avoid ambiguities, one should always write the width of the memory interface.
Most desktop computers and laptop computers have 128-bit memory interfaces.
The cheapest desktop computers and laptop computers, e.g. those with Intel Alder Lake N/Twin Lake CPUs, and also many smartphones and Arm-based SBCs, have 64-bit memory interfaces.
Cheaper smartphones and Arm-based SBCs have 32-bit memory interfaces.
Strix Halo and many older workstations and many cheaper servers have 256-bit memory interfaces.
High-end servers and workstations have 768-bit or 512-bit memory interfaces.
It is expected that future high-end servers will have 1024-bit memory interfaces per socket.
GPUs with private memory have usually memory interfaces between 192-bit and 1024-bit, but newer consumer GPUs have usually narrower memory interfaces than older consumer GPUs, to reduce cost. The narrower memory interface is compensated by faster memories, so the available bandwidth in consumer GPUs has been increased much slower than the increase in GDDR memory speed would have allowed.
Sadly motherboards, tech journalist, and many other places confuse the difference between a dimm and channel. The trick is the DDR4 generation they were the same, 64 bits wide. However a standard DDR5 dimm is not 1x64 bit, it's actually 2x32 bit. Thus 2 DDR5 dimms = 4 channels.
For some workloads the extra channels help, despite having the same bandwidth. This is one of the reasons that it's possible for a DDR5 system to be slightly faster than a DDR4 system, even if the memory runs at the same speed.
>However a standard DDR5 dimm is not 1x64 bit, it's actually 2x32 bit. Thus 2 DDR5 dimms = 4 channels.
Uh, surely that depends on how the motherboard is wired. Just because each DIMM has half the pins on one channel and the other half on another, doesn't mean 2 DIMM = 4 channels. It could just be that the top pins over all the DIMMs are on one channel and the bottom ones are on another.
I think there's a standard wiring for the dimm and some parts are shared. Each normal ddr5 dimm has 2 sub channels that are 32 bits each, and the new specification for the HUDIMM which will only enable 1 sub channel and only have half the bandwidth.
I don't think you can wire up DDR5 dimms willy nilly as if they were 2 separate 32 bit dimms.
Yes, but tablets, laptops, and normal (non-HEDT) desktops have 4 channels, 4x32 bit = 128 bit wide. Modern memory with DDR5 allows two 32 bit channels on a 64 bit dimm. The previous gen DDR4 would allow 1 64 bit channel on a 64 bit dimm.
So strix halo (on laptops, tablets, and desktops) allows for a 256 bit wide memory system, providing twice the memory bandwidth of any ryzen or intel i3/i5/i7/i9. The Apple pro (256 bit), max (512 bit), and ultra (1024 bit) lines of apple silicon have greater than 128 bit wide memory systems. On the AMD size it's just the Threadripper (256 bit) and Threadripper pro (512 bit), but those are typically in expensive workstations that are physically large, expensive, and need substantial cooling.
So the HALO is pretty unique (outside of Apple) for providing twice the memory bandwidth of anything else that fits in the tablet, laptop, or small desktop category.