Please describe your components, especially the brand and model (not just wattage) of the PSU.
What motherboard do you have? The bottom PCIe slot may not be x16, which might hinder your graphics card's performance. A second slot on many boards is only x4 lanes.
If your PSU is not up to the task of powering that card, it will get hot and the fan will ramp up until it is screaming trying to cool the PSU. Most likely, you are overloading it and it will either shut down (if it contains working protection circuits) or it will choke, smoke, and croak (if it lacks protection circuits). Worst case, it will take attached parts with it into the fiery abyss.