No, the internal graphics card may not be suitable . It can be dead, as any other component on your workstation. Sometimes only a part of the motherboard is damaged (the internal graphics card or some or all of its video ports may be broken in your computer), so it is better trying another one as part of the troubleshooting process.
I would suggest using the built-in self test (BIST) feature of the workstation PSU. This video from TechSupportDell may help you understanding the process. Any component may be failing. It is better starting with as few hardware as possible (e.g., motherboard, one memory module, a monitor and an USB keyboard) and, in case it works, adding more hardware and try to turn on the computer again. At some point you will either find the device that renders the workstation unbootable or discover that the problem was a bad connection of one of the devices.