I had the GeForce 8400 GS running on my old Dell Optiplex GS 280, which finally died and CPR didn't help.  I purchased a new Acer Aspire TC-280 and I tried to install that PCI Express Card in my new PC, but I can't get it to work?  I plug in the card and when I turn on the PC, the PC spins up but neither the DMI or VGA monitors display anything.  I unplug the card and I can get either the DMI or the VGA monitor to work, but not both.  That Acer has two video ports, one VGA and one unneeded HDML (unless there is an adapter that goes HDML to DMI).  I'm not a gamer, so I don't need much resolution but I do enjoy working with spreadsheets and having two monitors really helps.
  Will that GeForce 8400 GS card work with my new PC?  I had Windows 10 running on my old Dell and the new Acer PC also is running Windows 10.  I can't get the install CD to load so do I need to get a new Windows 10 Compatible CD?   I think they have changed the booting file structure since that old Install CD was made. 

I'm not familiar with the card or the Acer but even without drivers you should get a basic screen. A couple of basic things come to mind. If the card needs external power make certain it is connected and supplying power. Check the manual for the Acer and see if there is a bios or MB change that needs to be made to support a video card. Try the card in another computer and another slot in your new computer if you can. Nvidia drivers can always be downloaded from the Nvidia web site.
 
You did not say what your old computer died from. Could it have been the video card? What exactly do you mean by the install CD not loading? Does it not start the installation at all or does the installation fail after starting?

Sajin - thank you for your quick reply.  I'll try going into the BIOS and see what I can change.
 
aaronkro - Thank you also for your quick reply.  With either the DVI or VGA monitor plugged into the existing VGA port, the display works.  If I try plugging the PCI card into the only PCI slot that ACER has, and connect the monitors, nothing gets displayed.  Like Sajin mentioned, I may have to go into the BIOS and make some changes.  I don't know what caused that old PC to die, I started getting error messages, that would clear, then the PC just quit spinning up?  May have been the motherboard or power supply.  From what I could tell, two contacts on that four pin plug read about 5.0 volts.  The other two only showed 11.7 volts.  The range was +/- 1.5 volts, so from what I could tell, the power supply was working?
 
bcavnaugh -  Thank you also for that quick reply.  I noticed those driver downloads but I wasn't sure if I had to install the drivers before or after I installed the graphic card?  I didn't want to cause any problem to my existing display.
 
  You have all given me something to work on. Thanks again.

Thanks, keep us posted.

So sorry to hear you are having so much grief. Your experience is not that different from mine for many things and is one of the reasons I build my own rigs. When the scripted tech support can not find the answer on their cheat sheet the solution is always to reinstall the OS. Not going to happen. I'm sure after all the work you have put into this you have closely examined the manual that came with it for video options. Not sure what DMI is with respect to monitors, did you mean DVI? Anyway have you tried looking for adapters or cable adapters that convert whatever the port on the PC is to whatever you need on the monitor? You might be able to use the native video on the PC.

I assume the two monitors you have are 1 VGA and the other DVI. When you connect both monitors does one work and not the other? Have you gone to Display Settings and looked at the multiple display options? If I am not mistaken both monitors need to be set to the same display resolution.

What version of Windows are you running and is it 32 bit or 64 bit? Is it possible the PCI slot is bad? Is there another type of card you can put in the slot to test it out? Does the card have an external power connector and if so is it connected?
 

There are a few apps you can download that will tell you the makeup of your system. CPU-Z and Speccy are the ones I use. But be CAREFUL where you get them from and run your virus software against the downloads BEFORE you install them (if you need help with that let me know). Don't get them from Cnet. If you can, try and get them from the originator's site. Here is the summary page from speccy on my rig. The rig is new and I have not done any overclocking yet. As you can see speccy provides a wealth of information. You can also look at the details of all the components.
 
Also, I find it difficult to believe the bios on your computer is locked. Have you actually tried to access it and look a the video options if there are any?
 
speccy summary window:
Operating System
Windows 10 Pro 64-bit
CPU
Intel Core i7 @ 4.20GHz 28 °C
Kaby Lake 14nm Technology
RAM
32.0GB Dual-Channel Unknown @ 1070MHz (15-15-15-36)
Motherboard
ASUSTeK COMPUTER INC. STRIX Z270E GAMING (LGA1151) 27 °C
Graphics
DELL U2412M (1920x1200@59Hz)
3071MB NVIDIA GeForce GTX 1080 Ti (EVGA) 40 °C
Storage
931GB Samsung SSD 960 EVO 1TB (Unknown)
931GB Western Digital WDC WD1002FAEX-00Z3A0 (SATA) 33 °C
2794GB Seagate ST3000DM001-9YN166 (SATA) 32 °C
2794GB Western Digital WD My Book 1230 USB Device (USB)
4657GB Seagate Expansion Desk SCSI Disk Device (USB (SATA)) 33 °C
1397GB Western Digital WD My Book 1140 USB Device (USB (SATA)) 30 °C
Optical Drives
ATAPI iHBS112 2
Audio
Realtek High Definition Audio

So does SIV. http://rh-software.com