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DDR5 is something like 10x slower (or 10% of the bandwidth) of GDDR6 or HBM that's used on GPUs. There's no point going much wider on iGPUs, because they're al
by dragontamer 4y ago
DDR5 is something like 10x slower (or 10% of the bandwidth) of GDDR6 or HBM that's used on GPUs.
There's no point going much wider on iGPUs, because they're all throttled by DDR4/DDR5 anyway. The exception: PS5 and XBox both have GDDR (graphics RAM) which is 10x more bandwidth than your typical DDR4/DDR5. Since they are no longer memory-bandwidth constrained, they can go much bigger and remain practical.
- AnthonyMouse 4y ago> DDR5 is something like 10x slower (or 10% of the bandwidth) of GDDR6 or HBM that's used on GPUs. DDR5 is something like 50% of the bandwidth of GDDR6. DDR5 up to 8 GT/s, GDDR6 in the range of 14-21 GT/s. For example, the Radeon RX 6400 has GDDR6 at 16 GT/s. But it also has a 64-bit memory bus, compared to 128-bit for Socket AM5. So they have the same memory bandwidth, given the fastest available DDR5. Higher end GPUs have a wider memory bus than that, but those don't fit in the CPU socket's TDP anyway. It wouldn't prevent the iGPU from having 12+ CU instead of 2. Moreover, higher end CPUs have a wider memory bus than that too. Socket SP5 has 12 memory channels. And a max TDP of 360W. That's as much memory bandwidth as many midrange discrete GPUs, especially anything that would fit in its TDP with a reasonable power budget left to the CPU.
- AnthonyMouse 4y agoThey could also add some HBM as a chiplet to the CPU package. That would provide enough bandwidth to feed a fast iGPU and give the CPU a very nice L4 cache.
- sliken 4y agoMore like 2x. Apple for instance uses lpddr5 for 100, 200, 400, or 800GB/sec. It's mostly bus width, not the memory technology that makes a big difference.