1. I will certainely do that,... I just wanted to know if a GPU flash can higher the temperature the GPU needs to have before it activates its fans.
Tighter timings may have some temperature impact on memory temperature and indirect impact on core temperature (because if you have cards with proper cooling for vram chips they share same heatsink as gpu core, so you'll have slightly higher core temp if memory get hotter, but it's not end of the world. Fan speed depends on target temperature that you have in settings or bios (settings in driver will override bios ones, if set) and also acoustic limit.
2. I am aware that they have an order, and checked them one by one. I am 100% sure none of my GPUs were Micron/Samsung (only hynix and some Elspidia)
You can check memory manufacturer withing PBE itself (and you can have different memory inside single card, eg hynix/samsung). For example left one is hynix/samung combo (that will show hynix in gpuz, cause that have majority of chips); right one - elpida (whose manufacturer are micron, so technically microne == elpida):
https://image.ibb.co/en47Gn/image.png3. Yes I made a BIOS backup of every card (with GPUz), and will use them to see if the fans work back to normal. My cards are all different, and I modded each one of them and flashed them one by one.
Again, I'm sure they just have so relaxed fan curve and only spin when gpu reach high temperature (for prolonging fan life cycle and reducing noise when idle), so just change it in software and be done with it.
