There's a GPU Tweak II DVD thing but I don't know where it went if I found that will it help solve my case??Can you link to the page where you bought it?
There are a LOT of things sold on Amazon, that is NOT sold BY Amazon. Much like eBay, third party sellers have to be carefully vetted on Amazon because there is just as much chance of getting a fake or faulty product through one of them as there is through an eBay seller.
We can look at the power supply after we figure out a few other things.
What is the FULL model number of your prebuilt system? There should be a sticker on the case somewhere that lists the full model, or sub model, or express service tag, that will help to identify the exact components used in this build including the CPU and motherboard.
WHICH slot do you have the graphics card installed in?