ok well i was watching netflix on my hp slimline s3400f w/ upgraded gpu and psu (6450 gpu and 300w psu) then all of the sudden the computer turned ioff all the fans started to not work. So im thinking maybe its my gpu so i plug my VGA cord into the mobo graphics (nvidia 6150se) which that didnt work. But now whenever i turn on the computer some fan is running really hard (i dont know which one im guessing the amd 6450 gpu fan but im not sure) Could it be the motherboard thats not working.Im not getting picture on my monitor not even for the start up for the computer could it be overheated? i turn off the computer everynight and its normally on from 3:50pm to 10:00pm unless during the weekend which i dont know how late i stay up 12+. The computer turned off at 4:50pm so it wasn't even on for that longshould i let it rest? Or should i open it up and take the amd 6450 out? i really dont know what too do. please help
Read this ref, it's made for new builds but will help you. http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems
Does your computer make any beeping noises? The BIOS talks to you by beeping. You PC manual in the troubleshooting section will tell you things like 'x beeps means memory failed.' There is also a beep code for normal boot. If the PC used to beep and makes no beeps at all that says the BIOS is not completing successfully.
If the PC beep codes don't tell you what went wrong standard debugging is to pull parts until the PC works enough to complain about the missing part. For exampple, remove all memory. IF the PC beeps "no memory" that's good.
The order of removal is important. First pull all wires from the PC except power. Get rid of mouse, keyboard, network, anything USB like printer, etc. Does the PC complete it's power on self test (post)? No, time to pull disk signal and power wires, try again. No post, pull memory. Eventually you get down to just MB, Power supply and CPU.
When you upgraded the video and power supply did you keep the old power supply? The 6450 draws so little power it would work fine on your old pwoer supply. Swappign backin the old PSU is the first thing I'd try if pulling parts doesn't let you isolate the error.
Good Luck. post what happens.