Hi all. I'm new to this forum and was wondering if anybody can clear something up for me. I'm running a single GTX 580 Classified in Mac OS 10.8.2 with Cuda Driver 5.0.37, and NVidia GPU Driver 220.127.116.11 (304.00.05f02). Under Cuda-Z I do get PCIe 2.0 transfer rates, but in my system profiler, my GPU only shows PCIe 1.0 link speed of 2.5 GT/s. Am I really getting PCIe 2.0 with my GPU? And also I do notice that sometimes the CUDA-Z shows PCIe 1.0 numbers occasionally, but soon ramps up to normal PCIe 2.0 numbers. Attached is photo of system profiler and cuda-z. Any input is appreciated. thanks.