The game seems to prefer to run itself on a secondary low power gfx card instead of running on the main primary gfx card.
pc setup is as follows:
primary display 4k/uhd iiyama bg2888ushu => Radeon R9 290X => Pci-E 3.0x16 => i7-3770.
secondary (no monitor attached) => Nvidia GTX650 => Pci-E 2.0x4 => pantherpoint chipset.
tertiary 1080p HD medion => intel HD4000.
OS is windows 10 15063.608, 16G of DDR-ram.
same problem occurs in forza 6 (apex) , forza 3 horizon and now the new forza 7 (demo).
The game starts and i can see it choosing the GTX 650 to do it’s 3D work on instead of using the R9 290X which is displaying the game, So the game does choose the correct display attached to the R9 290X.
if i connect a display to the nvidia or not , this stays the same, the game allways starts up on the correct screen attached to the R9 290X. But the 3D work is actually allways beying done on the nvidia GTX650.
This results in low and choppy performance,
The only trick i find that works is dissabling the nvidia GTX650 in the windows devicemanager. Doing this makes the game run on the correct Gfx card = R9 290X.
It is a nuisance to say in the least to have to do this , also it only appears to happen in the Forza series.
since the GTX650 is there purely for physx matters, i do like to have it enabled even if forza does not use physx.
I find it odd that Forza of all games would show this behaviour, (almost as if it wants to run as bad as possible), i mean choosing a secondary on a chipset instead of primary on cpu got me puzzled.
the intel HD4000 does never pose a problem and the game never wants to use it anyway, it is only active for Quicksync.
several different drivers (all of the latest) don’t make any difference either, the problem persists and i have to dissable the gtx650 for forza to run smooth in 4k maxed out at around 90 fps on the R9 290X.
Hope this little quirck can be fixed before the release of forza 7.