Pc hang every time we played sf online our pc hangs what is the problem of our computer is it the memory?

Depending on what "SF" (which ever game that may be) requires you may want to make sure that if you are a windows user then to make sure you have the most up to date drivers for your video card and make sure you have sufficient amount of ram installed as well as video card requirements on your computer. most games these days games require a good hand full of resources such as call of duty 4? or crysis? half life 2, fear, any MMORPG games etc so make sure your computer has enough resources to run this game you speak of and make sure your not tying up other usefull resources on background applications you are running by either closing them or bringing task manager up and closing them that way (personaly i prefer task manager because it shows you what and which apps are using all your resources) make sure also that your DX (Direct X) is the most up to date (dumb comment but you would be amazed on how many users complain because they say everything is up to date but later to see that they have direct x 9 ver "B" installed rather then version "C" so please make sure drivers, software, game updates (if available) DX9 update and requirements such as ram, video card, video card ram are even suffient enough for that game to run smooth