Hello, i need some help with Mac Pro (mid2010) (quad core Nehalem) with Lion 10.7.5. I bought an MSI 570 Twin Frozer III Power Edition card (PC) and put it in the second x16 pcie slot (in slot 1 there is an Ati 5770) . But in the System report says that the Pcie lane width is only 1x and the performance is slow. If i put it in the first slot its 16x (unfortunatly half the bandwith 2.5G) I`ve checked the second slot with ati 5770 and its working at 16x. So i guess the problem is not in the mainboard. Unfortunatly if i put the ati card in the second slot i cannot put the nvidia in the first because its too big. So the main issue here is why i get only 1x from the second slot with nvidia 570. I would realy appreciate your help.