Not being familiar with the DDR4 spec, I wonder how much performance benefit DDR4 brings without increasing the size of the processor's cache line? As others h

Not being familiar with the DDR4 spec, I wonder how much performance benefit DDR4 brings without increasing the size of the processor's cache line? As others have mentioned, the latency for random access is quite high, and DDR effectively just multiplies the bus width. For DMA and filling cache lines DDRx is a win because you usually want to grab all those bits anyway (although in those cases, the addresses tend to be contiguous anyway, so it's not as slow as "random"). But if your cache grabs bunches of 512 bits, having a memory that is only faster when transferring a contiguous group of 1024 bits isn't an obvious speedup.