The all-in-one Raspberry Pi 400 computer is a capable device, but those seeking its maximum power may be disappointed by its 4 GB of memory. When the Pi 4 and Compute Module 4 have double that figure, surely the Pi 400 could catch up! A reddit user called [Pi800] rose to the challenge by replacing the 4 GB chip from the Pi 400 with the 8 GB chip from a Pi Compute Module, resulting in the so-called Pi 800, a working 8 GB all-in-one Pi.
As a piece of work it’s a deceptively straightforward yet extremely fiddly piece of soldering that requires a steady hand for even the most skilled of solderers. What takes it beyond the norm though is the reballing process. A ball-grid-array chip has a grid of small balls of solder on its underside that make the contacts, and these melt when it is soldered so require replacement before reworking. This is normally done with a template of carefully aligned holes to line up balls of solder in a stream of hot air, but lacking the template in this case the job was done by hand, laboriously ball by ball. A soldering task we’d hesitate to take on ourselves, so we’re impressed.
The result is an 8 GB all-in-one Pi, and it’s honestly not beyond the realms of possibility that an official version of this mod could be a future Raspberry Pi product. Perhaps we’ll wait for that, but should you be impatient then at least it’s possible to roll your own. It’s certainly not the first BGA memory swap we’ve brought you.
Source: https://hackaday.com/2021/11/08/hand-reballing-and-a-steady-hand-makes-a-raspberry-pi-800/
