So yeah, its my fault for not doing the proper research. I recently bought the Geforce GTX 660ti without knowing the proper required specs for the power supply wattage. The minimum amount is 450W for the card, and the computer I have is a HPE 400f, and the wattage is only 300. I don't want to install it now and have it burn out my computer. What should I do? Is it easy to buy an upgrade for an HPE power supply? Or should I just get a different graphics card? I don't think I can return it because I bought it from Tigerdirect and they only accept returns for certain products and video cards aren't included. Also I don't think it came with the right amount of PCI pins. One has six while the other only has five? Anyways, what should I do?