I tried to get a crossfire (2x R9 290X) to run with GW2 (32bit and 64bit) on a tiled 4k display (DELL UP2414Q). The game crashes.
For crossfire u need the full-screen non windowed mode. The moment I swap to that the game crashes.
- Using windowed full-screen so crossfire is not enabled works in both windowed and full-screen non windowed mode.
- Using a lower resolution like HD instead of UHD works and in crossfire in both windowed and full-screen non windowed mode.
So, only the combination of UHD and crossfire (full-screen) does not work.