Hi, first, welcome to the board.

Second, I wish I had an answer for you but I just have to comment that stealer was obviously only interested in making the sale asap. They should not have let you leave with the 285s on one side and 255s on the other - simply ridiculous!

Would not surprise me if that did have something to do with your current problems. Again, sorry I can't be of much help but there are plenty of knowlegeable people here that probably could. Good luck with your X!