New Nvidia 8400gs not being detected..........Please help.

I have exactly the same thing going on. I was told to remove the card, start up. When the blue HP screen come on, hit F1 to go to setup, then go to Advanced. Make sure the Primary Graphics Adaptor is set on PCIe. Mine was and is set on PCIe and it still does what you describe when I put the card in. Anyone know how why this is happening and how to fix it?

My screen is blue as well......I also tried to change it to the PCIe graphics option.......but nothing happened. I've been reading around and it might be the power supply. What HP model do you have? Its kinda frustrating.

Mine is a Pavilion a1473w. It has a 300 watt power supply. Today I was told it could be either the power supply or a chipset conflict with the ATI onboard graphics. I don't know if I should just return this one or buy a more powerful PSU.

A 300W PSU should run that card (assuming you do not have absurd numbers of hard drives and fans, ect.) I would look for other fixes.

I have 2 hard drives, 2 fans, onboard graphics and sound and a DVD writer. USB has 2 printers connected. Is this too much with this card.

Yeah, I was told the same thing. My PSU is only 250w. So what i am going to try to do is get a stronger PSU and get a different graphics card. Hopefully it will work. Wish me luck.

I think my GeForce card was bad. I exchanged it for a VisionTek ATI Radeon HD 4350. Disabled the onboard graphics, put the new card in, turned it on and it worked.

Thats cool..............yeah I just exchanged my 8400gs for an ATI 4550. Hopefully it will work.

I should have bought the ATI first but the 8400GS was on sale. Hope your install was as easy as mine was.