i installed a radeon hd 6950 on this computer https://www.overstock.com/Electronics/CyberpowerPC-Game... the computer specs are on the bottem of the link
theres no red light on the card wen it starts up i connected everything right i updated the bios and the motherboad drivers and disableing the on board graphics wen i put jus the pci e port on the computer dosent make a boot noise it stays on but nothing happens when its like that
if anybody has anymore sugesstions please let me know
That's kind of a lame PSU. I'm not sure if the HD6950 would really run in it with all the other stuff you have in it already. It has alot of amps on the 3.3V and 5V rails, which today is not really that great, since most modern components use 12V rail power.
This could lie the source of the problem. On a full load, the 6950 uses 180W, which is about 15a. That might not sound like alot, but it kinda is. The power supply is not always efficient in transferring AC power from the wall to DC power. Sometimes the energy is lost, such as in heat.
Anyway, long story short, most likely the power supply is not enough for the computer. I would say a GOOD 600W would be enough to power your system.