I have a DL380 and a 24 inches monitor HP Z24n and they were working OK until I replace the video card from Nvidia K620 to Nvidia NVS450. At this point, the DL380 couldn't detect the Z24n monitor. I put again the Nvidia K620 and the problem is still there.
The DL380 has a VGA port which I used to run a test and I saw:
error: no such device: HPEZCD260
I think this post can help me, but the links you posted are not available anymore.
Someone can help me please?