it shouldn't be, considering thats not how PCIe works, assuming the first card is plugged into the first slot and has a full x16 bandwidth, and additional cards will get x8, because the only other two slots are the board are x8, in SLI mode it will run in x16/x8 mode, not x8/x4 or x8/x8, or x16/x4, even if a sound card is plugged in, it will run x16/x8/x1