I've got a Pi 3B+ and I'm thinking of upgrading to a 4B, partly to free up
the Pi 3 to do other tasks.

I've got a couple of questions?

- Can a "system disk" SD card (ie the same disk image) for 3B+ be used for a
4B? Is it a case of "yes, but you won't be making full use of the 4's 64-bit
architecture and larger RAM"? I'm being lazy and avoiding installing and
configuring everything all over again unless I have to ;-)

- I've read reports of the Pi 4 running quite hot and needing a cooling fan,
as opposed to just passive heatsinks, when used in a case.


I'd be using it for recording TV (using external USB DVB decoders) to a
spinning disk (*) (not to the SD card), using TVHeadend, for SMB-sharing
folders which are accessed by Windows PCs, and maybe also for running simple
software such as a browser or an email client. On my 3B, the CPU usage is
barely measurable for recording from three different sources simultaneously,
while serving one of the video files to a Windows client, but it shoots up
to nearly 100% as soon as I run Firefox or Chromium, even when a static page
has been loaded. Is it a known problem with the Pi 3 (maybe fixed on the Pi
4) that browsers tend to hog the CPU?


(*) Driven by a powered hub, not by the Pi's PSU.

--- SoupGate-Win32 v1.05