It really depends on the board, if the manufacturer has allowed a bios update to support the q9550, but the lga 775 chipsets you'd look for would be:
b43, g33, g35, g41, g43, g45, p35, p43, p45, q33, q35, q43, q45, x38
will it be able to play fortnite and gta V? yes, well? No. perhaps 30-40fps.
I wouldn't trust
this site 100%, but it should guide well enough.