A report from TechPowerUP has just confirmed what we expected: the RX 480 can be flashed to RX 580.
Turning Polaris 10 XT into Polaris 20 XTR
As I mentioned yesterday, there are two types of Polaris 20 GPU, the XTX and XTR. The latter has higher frequencies and should be used only on higher-binned chips. However, it seems that it works even for old RX 480, which were also sorted by ASIC quality, but for lower voltage (as you probably already know, voltage was increased for RX 580).
The BIOS from Sapphire Limited Edition was successfully transferred to XFX RX 480 graphics card. This unlocked 1411 MHz clock speed out of the box which was verified by Witcher 3 and Furmark testing. This obviously means higher power consumption and maybe even lower lifespan of the GPU, which was not tested with such BIOS.
In other words, it’s not recommended to flash the BIOS unless you are absolutely certain that this might improve your experience. Of course, BIOS flashing is not really that extremely difficult these days, but it’s much easier and safer to do on dual-BIOS cards.
The RX 480 to RX 580 mod was also verified by someone from Coolenjoy, who did the same thing with his RX 480.