Nick Devlin writes he got approx. 1.5 GB per minute off a SanDisk Extreme IV card while Sanho claims 2 GB per minute with fast UDMA cards (which the Extreme IV certainly is).
When comparing claimed vs. real-world transfer rates, please note that manufacturers of memory cards, hard-disk drives, and image tanks usually think of kilo-, mega-, and gigabytes in terms of potencies of 1,000 while computer operating systems and their file browsers calculate on the basis of 1,024. Based on 1,000, one gigabyte is 1,000^3, or 10^9 bytes. Based on 1,024, one gigabyte is 1,024^3, or 2^30 bytes (according to the IEC
, the latter is also called gibibyte, or GiB for short ... there also are kibibytes KiB = 2^10 = 1,024 bytes, mebibytes MiB = 2^20 = 1,048,576 bytes, and tebibytes TiB = 2^40 = 1,099,511,627,776 bytes).
So if Sanho claims 2 GB (2,000,000,000 bytes) per minute then that really is 1.86 GiB per minute in your operating system's terms. If Nick also thought in GiB (and, by the way, 1.5 GiB = 1.61 GB) then the gap between claimed vs. real transfer rates is even less than it seemed at first sight.