"No input" after installing Nvidia GeForce 9800 GTX+

grinch

TS Rookie
My old video card (Nvidia GeForce 8500) overheated and stopped working. I ended up buying the Nvidia GeForce 9800 GTX+. I just got it this morning and installed it. I think I have everything plugged in correctly, but I am not 100% sure. When I tried booting my computer up all the fans were working, but my computer didn't start up. On my monitor it said "No input signal." I've been trying to fix this for the past few hours now and I've exhausted all possible options. Can someone please help me? I have a HP m8000, I can try and find any specifications if needed. Thanks for your guys help!
 

grinch

TS Rookie
update

After uninstalling all the old drivers and using driver sweeper it worked and asked me to reboot and select the boot mode. When I restarted it, it went back to the same "no input" signal. I really have no idea what's going on, is this a power supply issue?