So recently i've gotten into PC gaming. I got a 2008 HP Pavilion tower PC from a friend and put an AMD Radeon 6870 graphics card and a new 520 watt PSU in, but games like minecraft (Which system requirements lab says should run great on far render distance) still have lag. If anyone replies, I'll post the full specs. I've already updated the drivers, so is there any reason why this should be happening?
(I cant access the computer right now, but i know it has an intel quad core CPU @ 2.20ghz.)