I would agree. It sounds like they knew something was wrong with that part of the board from either testing or experience. I'm surprised they changed a PCIE slot and not just give you a new board. I would approach them again and tell them it isn't fixed.
No not at all.. It means that it's stopped using the hardware to accelerate the graphics. It doesn't give a reason why and could be down to either the driver, gpu or gpu slot. (which really you kinda knew already)
okay.. I will take this to repair PC shop and lets see what is the faulty thing.
Can the PSU be bad?
What ever forum I am visiting with same problem says the keyboard jamming / off is happen because of mobo.