Ummm how can i know if its in good condition or not?
sorry for many question i'm beginner
It can only be decided when you realize that things your PSU should be powering , it can;t do so effectively any more....
What I implore you to do is to go ahead and buy the graphics card and install it, that is the only way you will know if it works... If it was a PSU below the minimum requirement for that graphics card, then I could say definitively that it wouldn't work.. But your PSU is 400 wats, so once it is working well it should be ok... And don't be scared to get the graphics card, the PSU not working up to potential will not damage it.