i have a 250w power supply and im getting a new one
thats 550 and a new 1gb graphic card and im wondering if it will over heat?
im really worried if i get it and it overheat everytime, do i need more fans?

this is not the place to post this but, yes, you need more fans.

wow 250w

how old is this pc? must be at least 10yrs old

Overheating isn't caused by having more power, it's caused by hardware ( such as your CPU, RAM, GPU ) working harder than it usually does. Download a program called coretemp ( You can google this ) and it gives a good indication of how hot your computer is running, 30-40 degrees when you are running a full load is about normal. If you are running hotter you need to look into cooling.

Well, you shouldnt have a over heating problem at all, Decent GPUs all have built on cooling, but however if you plan on over clocking the GPU to give out more then you need sufficient cooling

what Im trying to say is, don't mess around with GPUs settings with programs that comes with the drivers if you dont know whats going on.

I wouldn't worry about it. Dust buildup and hardware like the CPU causes heat.

Keep your fans relatively dust free and don't cram the tower somewhere that won't have air flow. Hardware is tested to ensure it's oem cooling system is sufficient enough for the hardware to function under normal conditions by the manufacturer.

Everyone is pretty much right:

• Make sure your case has good airflow.
• Make sure your fans are pointed in the right direction to get the most efficient airflow:
  • Front, side, and bottom are generally intake.
  • Back and top are generally exhaust.
• Make sure your hot PC components (CPU, GPU) are not in too close of a proximity to each other which will cause the temperature in your PC to rise.
• Make sure you adequately clean your PC so dust build up does not hinder air cooling efficiency.
• Make sure your PSU supports your total overall PC power consumption

Most BIOS' have an option to warn you if the temp goes above a certain threshold. Just make sure before you switch out all the equipment to clean out as much dust as you can while the major components are out like that. From all the fans, and you will be just fine barring unforeseen catastrophic failures.