Both V3 and V4 are perfectly compatible with Switch V2. The only difference between the two versions of hwfly is the ability to upgrade bootloader (software of the core chip - only V4 can do).Hello, a really noob question here: What do I need to know before getting my V2 switch modded? My local vendor has a V4 and V3 hwfly chip and he said that the V3 is more compatible. I don't know which one to get and have no idea about about the custom firmware and stuff. Thank you for taking some time to read this. Have a good day!
Because in OLED switch, Nin has changed a little bit design so that if using hwfly v3, it will silently, slowly kills OLED CPU (voltage different between cpu pin and hwfly pin). That's why V4 comes out as a solution for that problem: update bootloader, change a little bit voltage output,...
V2 switchs aren't affected by this problem, so which hwfly version cheaper is better in this case. You can save a little money for another accessories.