According to the owners manual the first few lines of the BIOS/System Setup section indicates that the amount of memory dedicated to the integrated graphics and the ability to enable or disable it are options in the BIOS. The BOOT method is Legacy instead of UEFI, the BIOS has been reset, default options loaded, etc and no where are the specified options visible. BIOS is version A7 which I believe was the version that it was shipped with and the latest. This is not a huge issue, but the fact that the option is missing from BIOS and needlessly using a bit of RAM is enough to see if anybody is aware of an issue.
I haven't contact support yet as I just got the box yesterday as a replacement machine at work. I have already torn the thing apart looking for the old school jumper method of turning off the integrated graphics with no luck there either.
Just a bit more information. The add-on card is a NVidia NVS280 or NVS285 LP with pigtails to dual VGA. With monitors hooked up to that card it has worked perfectly fine so far. I haven't tried one monitor on the integrated card and the other on the card to verify both are still working, but the Intel integrated graphics still shows up in device manager and is using system memory.
I just bought a card for my Vostro 270s, and will run into same issues. There are no instructions as to what to do when. I suspected that I would have to reconfigure the bios to use the new card, but it sounds like we can't disable to onboard?
I made it work by putting a display emulator on the internal HDMI and using Windows P to telling Windows to display on the 2nd adapter. It remembers this through reboots.