youcan help yourself by checking for information on graphic cards terms over the internet....i got one for you on RAMDAC...the rest u have to help yourself since it is u yourself who wanted to know all
http://www.auditmypc.com/acronym/RAMDAC.aspi got another link from HWZ forums on a little more details with graphics technology and what to choose from the lot here
http://forums.hardwarezone.com/showthread.php?t=1233319first identify what u want to use the graphics card for (office applications? videos?games?large/ multiple screens? etc) and work towards a budget and hardware specification that suites you.
