...

I will investigate, but I will also be on the lookout for a new motherboard.

...

Motherboard replacement

The AI5TV motherboard is a “Baby AT” form factor board. Other boards that have that form factor and which might fit are:

• https://theretroweb.com/motherboards/s/jetway-j-849bs

• https://theretroweb.com/motherboards/s/shuttle-hot-685

In the end I opted for Soyo SY-5BT5 2.x:

• https://theretroweb.com/motherboards/s/soyo-sy-5bt5-2.x

This fits rather nicely.