I bought a few days ago a Nitro Sapphire AMD R9 390, after uninstalling with DDU and after re-installed the latest beta drivers have tried the games until a few days before I played with a HD 7870, I noticed that in some games the card does not express the full potential, as you will see in the video that I recorded the GPU works at sobbing like there's a limiter, I tested in all modes, without vsync of course, but the fps are not blocked because they reach based on visual even higher values, I can also see by the ammeter if the board is working very hard or not, and in fact, consumption is much lower than in other situations, for example in beta starwars board goes as it should, always gpu at 100%, then it's not even a hardware configuration problem, I think the drivers have serious problems dealing with energy conservation going completely haywire.
The game in question is TESO and tried it with a 970 too, I did screen at the same point with all three video cards to have a benchmark of performance, the 7870 achieves 55fps (230W), with 970 83fps (250w) with r9 390 50fps consuming 300W !... even with the use of GPU unstable and almost always lower than the 99%, increasing the resolution up to 4k with VSR fps remain the same and the energy consumption increases to almost 400W!
If this is the real situation of last AMD card i will send back for a 970..
I think one 390 should be pair at 7870 crossfire or better, but like i see is only energy drain card.
I have already set limit power at +50.
this is the video:
and i'm not the only:
I5 2500k @ 4,4Ghz
Asus P67 Sabertooth
16Gb DDR3 1833Mhz
CoolerMaster Silent Gold 600W
SSD 250GB 840 Pro
I ran furmark in fullload at 500W for test power supply and all work stable.