how much ram will my Dell OptiPlex GX620 take

[inviisabl3]

hi i have brought a Dell OptiPlex GX620 from ebay and want to upgrade the ram but i dont know how much ram it will take or where to get it from please help

also what are the best graphics cards i can get for it

thanks

 

[Ghostman 1]

You can put in 4 gigs Max..