I have the Lexar 300x (45MB/s) 8gb card also. It has worked flawlessly for 2 years but I recently decided that I needed a larger card and Best BUy had the Sandisk UDMA 60MB/s 16gb card on sale. The first one I bought rattled, the casing was not sealed properly. So I returned it and got a new one. No rattle on that one but I was doing a shoot and couple hundred pics in, my 5DII froze up with an error message. I had to remove the battery shot a few more shots and error. Turns out it was the card. I was able to retrieve the images and then I returned it. I gave the Sandisk one more try and the 3rd one was a charm. It has been working flawlessly for about 4-5 months now. If I buy anymore cards I'm pretty sure I'll go with Lexar.


With the Lexar FW800 UDMA card reader, I'm pretty sure I've transferred 8 gig (250 RAWs) in about 3 minutes. I could be wrong but I think that is what I got with Lexar 45MB/s 8 gig card. I can't test it, I don't have a full card around. I have a Mac and the FW800 is on the MoBo and doesn't go through a PCI bus. I don't know the specs on PCI buses these days but I think that may play into it too. Could be driver issues too. Make sure you have the latest drivers for the FW Card.