Hi,
Firstly, your post will probably get deleted, as this is a forum for official installs only - people who illegally sell Recalbox systems are frowned upon, and any such systems do not get offered any support.
However, I actually can vaguelly remember this very issue from years ago - you must have an old version of Recalbox ?
We are now at v8.02
And, there are NO PS1 games of even close to 3 gig. Each game came on a cd, so the maximum iso image per cd would be 700meg, but very very few even got close to that - Crash Bandicoot is just 180 meg for example if I remember right.
If you have v7.xx, you should be able to plug in an ethernet cable and update to v8.02 without losing anything in your setup