Benchmark Results: Read/Write Throughput
H2benchw confirms the results we’ve seen in CrystalDiskMark 3.0, and it also helps to further break down performance. We see that the UHS-I cards not only improve peak performance, but also provide a significant increase to minimum transfer speeds. This might be even more important for everyday operation than impressive performance peaks.
The new UHS-I cards deliver significantly better peak and average write speeds, but they also drop to a bit more than 10 MB/s here and there. One card even slid to 800 KB/s speed during this test, which monopolizes each card's full storage capacity. This means that there is no guarantee that cards like SanDisk's Extreme Pro can actually maintain their performance levels at all times.
This is certainly not very important, as camcorders and digital SLR cameras work with internal buffers that can help mitigate performance bottlenecks. But it's worth considering this phenomenon. Users who don’t need 40 MB/s write speeds, but insist on the highest possible minimum transfer speeds, should still consider some of the more established (existing) products.