Can you indentify what graphics card will work?

[yhloeb]

What graphics card will work? (The PC has no OS. It's a old Dell optiplex)

 

[Crix525]

Here is the deal, an old dell optiplex usually uses the lga 775 socket which only compatible Core 2 series. And considering how old it is that is probably a PCIe Gen 1 slot. You could probably run a gtx 750 ti on there, but anything more powerful than that will be severely bottlenecked by your CPU. Be carefull with the GPU you put in there though, because PCIe Gen 2.1 will not work on that motherboard. This is all the help I can give you with the very little information you have provided.