I recently attempted upgrading my hp p665w computer. It had all stock parts save for a 300w psu and an old, but better than the built in graphics, card from a friend. I replaced the default cpu with an AMD Phenom II black edition cpu, the old graphics card with a Geforce GTX 650Ti, and the power supply with a 550w XFX psu. All seemed to be going well as I replaced these parts. I took care not to move the computer while working on it, I made sure to discharge any static I may have had as well as grounding myself during the process. Upon plugging the computer back up though I noticed that it would not stay on. I counted 7 seconds repeatedly as its time when it shuts off. I opened the case back up to check the motherboard for any touching metal as well as unplug and replug the psu wires to check for good connections. I still had the same problem though. It appears nothing is wrong with it aside from it not staying on. The motherboard lights up green with its LED, the machine beep as it turns on like usual, all the fans spin and I cleaned the only dusty one, but still the computer fails to stay on. I would really appreciate some help with this if anyone knows what could be causing such an issue.
Sounds like it could be an overheating issue because 550w should be plenty for your setup. Turn it on and leave the case open, if you see any fans not spinning then make sure they are plugged in or replace them. If all fans are spinning make sure you applie thermal paste to the CPU, if you didn't do that then the overheating and shutting off make sense.
Well if you replaced three parts at once why don't you say put the old PSU and video card back in place then see if boots up. If the samething happen probably the CPU. If it boots then say replace the PSU and again see what happens etc.
I changed the cpu back to the old one and a small metal piece fell out of the fan. not sure where it goes but that was probably the problem. it is a small square with 4 prongs on2 sides. I am also now having a problem with the graphics card not installing its drivers. I get a message that says "NVIDIA Installer cannot continue, this graphics driver could not find the compatible graphics software"