there is...but its covered by the metal thingy ( my mobo seems to have 2-3mm of space from the very back end of the case which seems a bit too much but I am ALMOST positive I mounted it correctly and it would take 2-3 hours to take it out to check ) There are 2 rectangular visible holes in the gtx metal thingy that lead out to the case but I cant put screws in em since they are just rectangular holes but I slipped a black plastic zip tie through ema nd tightened that as best as I could.
I wish I could find a fellow thermaltake armor case and Gigabyte P35 DS3R owner and see if they had this same problem.
