I don`t know how exact you can adjust memory access to GPU memory, but ppl that compare and cry here thet RX 4xx should be fast as 390x should first learn that any architecture is different, the driver is accessing GPU memory as best as it can, if zcash need many small accesses and if 256bit bus is not wide enough its logical that 384 or 512bit bus will be better, even when we know with 2xx and 39x GPU and memory clock is more "aligned" and in sync then on RX cards which usualu work 11xx/2000
CRYING here RX4xx is pointless if you know NOTHING about internel GPU arhitecture and even less about zcash prof of work algo and how its computed
Even if 480 and memory bandwidth 256bit bus still only used 50% of its capacity !!! And I think that the manufacturer knowingly went to such a move is likely for this new chip Polaris dostochno and bandwidth 256bit bus, with his new memory controller that provides a slightly lower performance than the 390 !!!
Sorry for my English
That would see the controller load from 390 models think it will give a small concept in this issue
On my 290 memory controller load is rarely over 60%. Big difference is that beside 290 memory bus being 2x wider, memory runs at 1250 MHz vs 2000 MHz on your 480. This means that you can do all possible tricks but no way can use that tight timings as on 290 at 1250 MHz or 390 at 1500 MHz. OK suppose that you reduce mem clock on 480 to 1500 or 1250 MHz to get the same timings but then you still do not get the speed that is possible with 2x wider bus.