I doubt if your motherboard has any extension slot for a dedicated GPU (AGP or PCI Express).. Moreover, the PSU is too weak to handle any good card.. You should really look forward to setting up a new rig..
this cpu has pci X16 slot
the card doesnot fit because the cpu is slim
My friend told me to remove metal bar and then fit it..
i tried that it works but i want to now is it safe to that
is it going to harm the system or not
What you need is a "low profile" video card but the 8400GS is terrible for gaming anyway. Look for a low profile HD4650 like this one; http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Your processor is insufficient for most current games but the card will allow you to play older games well.