Thinkpads Forum

Hi, guys! Sorry for the non thinkpad queation.
I found one of this old computers online and wanted to know what size of motherboard is compatible, so i can, maybe, build a sleeper in it with My current setup (i have to fit a rtx 3090 in there too). If I remember correctly my Mobo size is atx.
Thanks!

Please post pictures or links to photos of the computer (especially the rear panel)-- there's no way for us to know the specifics of each and every model of the Aptiva series.