Sorry for the late reply. I tried my dad's ATI 4350 and the error stopped. I used it for 15 hours straight, not a single error, or slowdown. Usually the error happens around 5 minutes within using the pc. Today i took it out because my dad had to use it and my computer's been running long hours, around 10 hours and it's working great. I can't play any games though, but that won't be a problem since the person who's buying it just wants it for music and internet. I have a feeling the error might come back but it's working great for now
Thanks for all your help, much appreciated!