The patch cables are all brand new Cat5e, but I went ahead and swapped it out anyway. vCenter still shows 100mbps.

The switch is HP Procurve 1810. The management interface reports that the NIC-in-question running at 100mbps half duplex mode.

I looked around in the BIOS of the host DL380G6 I did not find any settings related to the NIC speed.

Appreciate the help. Any other ideas?