Good afternoon, Going to preface this by saying I purchased a used 2010 Mac Pro yesterday. I was totally on the fence for awhile but I can safely say now I absolutely love this thing. So fast! I was surprised at the great performance considering the nearly six year old hardware, but it's perfect for my needs. At any rate, the 7200 drive it came with is relatively decent which surprised me but I installed an SSD drive to use for boot and the OS. I popped in a SATA III PCI controller card and attached the SSD drive to it and it's running fine, I'm just not 100% sure if it matters which empty PCI slot I put the card in. I know there are two different PCI slots (2 of them are x16, the other 2 are x4 or something). The Nvidia 680 Mac vid card is in the bottom x16 slot. Any discernible difference or recommendation for which slot to use? Thanks in advance to whoever can answer my question.