Posted 13 May 2011 - 07:38 PM
I'm not 100% sure, but I heard PCI express bus is slower than native USB 3. If this is true, it may be better to use the native USB connector from your MB than to use a PCIe adaptor.
Technically speaking, yes it is slower. PCI-Express 2.0 x1 only has 4Gbps of bandwidth (500MB/s) whereas the USB 3.0 standard can go up to 4.8Gbps, and the bandwidth is shared across those two ports. In reality, the speed difference compared to USB 2.0 is so striking that I don't think it would even matter. Plus, you'd actually need to have a transfer that is saturating the bus, and unless you're transferring data from a 6Gbps SSD hooked up via USB 3.0 to an internal 6Gbps SSD, the hard drive itself is going to be your bottleneck.
Primary Mac: 2011 15" MacBook Pro 2.2Ghz Core i7, 240GB OCZ Vertex 3, 8GB RAM, ATI Radeon HD 6750M 1GB, Mac OS X Snow Leopard 10.6.7
Primary PC: Intel Core i7 2600K, 8GB DDR3 RAM, MSI P67A-GD80, Corsair Obsidian 650D case, ATI Radeon HD 6950 2GB, 120GB OCZ Vertex 2 SSD, 27" Apple Cinema Display, Windows 7 Ultimate x64 SP1
HTPC: Intel Core i3 2100, 4GB DDR3 RAM, Gigabyte H67-USB3-B3, Thermaltake Element Q case, ATI Radeon HD 6570 1GB, 60GB OCZ Vertex 2 + 120GB Hitachi HDD, Antec Veris Multimedia Elite VFD, Samsung LN46A650 HDTV, Windows 7 Ultimate x64 SP1
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