Ever since I bought my Raspberry Pi 4B with 4 gigs of ram, I have had issues with random reboots, instability on startup and having to turn power off and on multiple times for the thing to boot properly. Also some disk clicking for a USB conventional portable spinning hard drive, and infrequent reports of undervoltage on shutting down. I always hoped the OSMC updates would fix these, but they never did.
When I bought the RPI, I also bought a kit with a case, a power supply, and a couple of heat sinks for under $20 USD. And therein was my problem.
Although the Raspberry Pi website states a 3000ma (3 amps) power supply is sufficient, it turns out it wasn’t. After getting more and more of the undervoltage complaints on shutdown, I took a chance and bought another power supply online that puts out 3600ma (about 20% more). After a good ten days of use, I’ve had no problems. So if you’re having problems and are using a 3000ma output power supply, it might be something to try.
I did not go with a 4000ma power supply because more power = more heat , so I was only trying to solve the power problems and not cause myself any other issues.
You got the right idea, but to clarify the part that isn’t quite right, A Raspberry Pi 4 will work perfectly fine with a quality 2A power supply if it isn’t connected to external devices with a significant draw of their own. As a matter of fact the Pi most of the time is drawing less than 1 amp. The problem that many people run into is that many power supplies have bullshit ratings. They may be able to supply 5v and they may be able to supply 3A BUT they are unable to supply both of those numbers at the same time. This is why phone chargers have always been discouraged for powering SBC’s as they tend to have their voltage drop as the current load increases. You can purchase a junk PSU that is massively overspeced and this will often solve the issue, but a quality PSU that is designed for the application will also work without overrating it.
No, inefficiency x load = heat. If your drawing 3A from a 3A PSU this, with all other things being equal, will be less efficient and thus produce more heat than drawing 3A from a 4A PSU which will also be stressed less and therefore likely to last longer.