Acer AW2000h-AW170h - Manual (Page 58)

3 System upgrades 42
4 Screw in two diagonal screws (i.e. the #1 and the #2 screws) until
just snug. Do not fully tighten the screws or you may damage the
CPU.)
5 Add the two remaining screws then finish the installation by fully
tightening all four screws.