Intel has finally confirmed that there will only be four Arc “Alchemist” desktop graphics cards in the retail channel. This lineup will of course be led by the Arc A770 Limited Edition, which will max out the DG2-512 silicon. As far as memory goes you are going to get 16GB of GDDR6 running at 17.5 Gbps across a 256-bit memory bus. That will equate to 560 GB/s of memory bandwidth.
Moving down to the Arc A750 it will have 8GB of GDDR6 memory running at 16 Gbps across a 256-bit memory bus. This will give you 512 GB/s of memory bandwidth. It also turns out that the Arc A580 features a 256-bit wide memory bus, not the 192-bit that was reported previously. This means it will have the same 512 GB/s as the A750.
Via Intel Graphics