But when I use this cheaper card, switching from 600 MHz to 1400 MHz immediately makes accessing the card fail:More frequency = more power. First thing to check with flaky SBCs is always that there is enough juice on the power rail. Spent half of last week troubleshooting why one of my Pis chewed through USB sticks. Problem went away when I switched to a non-LED backlit USB keyboard.
Indeed! I've found good ways to over-power my Pis, like powering both via micro USB and via the header pins, and/or using USB-SATA drive cables that have an additional feed that ends up backfeeding (as long as power for everything come from the same source, of course).
Power isn't an issue in this case, even if the cheap card somehow needs much more power than the Samsung.
Speaking of issues we know about, I need to reply to a different message here...
Thanks, John