Windows 7: GeForce 8400 GS detected, but not transmitting

My nVidia GeForce 8400 GS is seen by the device manager and seems to be working, but it doesn't seem to transmit video signal.

I just put a fresh installation of Windows 7 on my PC, I have the latest drivers, and the graphics card worked with Windows XP before I changed the OS. I am currently working off of the on-board graphics via VGA, but when I try to plug my monitor into the nVidia card with the DVI (same monitor, different source), the "Screen Resolution" window doesn't recognize the 2nd input. I also cannot get any signal from the card if I boot up with either cables plugged in.

I don't see anything in the device manager or in the HWiNFO32 program I have that throws any red flags. It appears to be working fine. And BIOS doesn't have any settings that should be interfering with the card working properly...

I'm pretty tech-savvy when it comes to computers, but I'm still learning Windows 7 (as opposed to my vast experience with XP). Am I missing something? Maybe the card went bad about the same time I installed Windows 7? Help would be greatly appreciated!

(Updated system specs since posting)

When you boot up with the 8400 does the monitor show any of the bios stuff? Make sure monitor is on first...

You can try to reseat the card/boot up without the card/shutdown...reinstall card....try to boot from the card....

Slim chance it's a bad PSU....

Just a thought: have you tried disabling the onboard graphics.

the monitor does not show any BIOS when plugged into the 8400. the monitor tries to read signal, displays the message saying there is no signal available, then "sleeps".

I still haven't tried to re-seat the card since the computer is slightly difficult to get to, but I'll try that.

and yes, I've tried disabling the onboard graphics through the device manager, but it puts in a generic VGA driver and still works anyway (and doesn't switch to the 8400 card).


I'm thinking I probably need to find a new card to see if it's an issue with the card, or if it's motherboard/hardware/Windows 7 related...

I actually have an identical machine with a GeForce 9400...same issue. Cannot get a 2nd display working (or any display through the card). It shows up in the device manager as the correct card with the updated drivers, but the Screen Resolution window doesn't detect any monitor through the GeForce adapter when I plug a monitor into it. I can view every property and setting about the GPU, but can't get it to actually do something for me.

Actually, now that I think about it, I believe the BIOS is version 1, from 2003...could updating the BIOS fix this..?


EDIT: A GeForce FX 5500 works just fine. Maybe it's an issue with nVidia's latest driver for those series of graphics cards?

The only problem is when it doesn't show any bios stuff at that time no drivers are loaded....have you tried a different PSU?

Well, as I said, I have an identical machine with the same problem, and the card worked fine last week on Windows XP, so it shouldn't be a bad power supply then, right? (No, I haven't tried a new one..)

No it shouldn't, but a PSU is a easy check compared to bad motherboard pci slot....The bad sign is the cards never work....even before the OS loads...about all that's left is PSU/motherboard/cards and since the 5500 worked, if it uses the same pci/pcie slot that just about eliminates motherboard....