If use second graphics card as physx dedicated, the debris will not appear (still have decal)

need to set physx setting to main graphics or cpu to work properly....

i don't know this is game's bug or Nvidia 's flex restrict, so i just report in forums....

P.S.

main card: GTX970

sec card: GT440

driver:361.91 win10 64bit

With a 970 does using a second card for physx improve performance? I'd have thought at that point it would be negligible with that card.