Thanks, so the benchmarks results are correct.
So either SDHC-interface from A570IS is slower than G7, or 4GB card performs worse than the 2GB cards, although it achieves 20MB/s in card reader. I will benchmark the Transcend 150x 2GB in my a570is.
So, okay did a little benchmark session on the A570IS (FW: 101a):
Transcend 2GB 150x (FAT16, freshly formated):
10003 KB/s
9600 KB/s
6660 KB/s
6159 KB/s
SanDisk Extreme III 4GB (FAT16, freshly formated):
10979 KB/s
10502 KB/s
5728 KB/s
5957 KB/s
SanDisk Ultra II 512MB (FAT16, freshly formated):
9786 KB/s
9752 KB/s
6301 KB/s
5872 KB/s
As the benchmark results vary quite a bit, i would say, all of them have about the same performance, and they max at about 10MB/s
None near to 20MB/s.
So the G7 seems to have a higher SD card performance. Lets check the code, to see why this is so
Edit:
Read the simplified SD specification, it could be the difference between normal speed and high-peed mode:
"High-Speed mode increases the bus clock rate to 50MHz and the SD bus throughput from 12.5MB/sec to
25MB/sec."