Firebrandx has just posted an interesting discovery on his Patreon page and I wanted to post his findings here (with his permission): https://www.patreon.com/posts/ssds3-ditch-your-30815328
In most ODE’s (Optical Drive Emulators) and ROM Carts, it’s common to hear a “buzzing” sound when the SD card is being accessed. It’s most often noticed when there’s silence in the game, as there’s no other sound coming from your speakers to mask it. This never bothers most people using ROM carts, as the sound only occurs once as the game loads, however some ODE’s are constantly accessing the SD card during gameplay.
In FBX’s testing, he recorded audio of the SD access and confirmed the rumors that a specific model Transcend MicroSD card (linked below) can be quieter than the more commonly used SanDisk cards. Here’s an audio recording that plays the San Disk card first, then the Transcend second. Depending on your speakers, you might hear more of a frequency difference, but you should be able to get an idea: https://www.retrorgb.com/assets/SSDS3-Sandisk_vs_Transcend2019.flac
I’d still like to know why this happens! Is it a read speed issue? Shielding on the card itself?
For now, I have no plans to replace my SanDisk Extreme cards, as I’ve been using these on my ROM carts since I first bought one and I haven’t had a single one fail. I’ll try out the Transcend’s as soon as I get a chance though and may switch to these for future purchases!