Why are the ethernet LEDs amber?

Hello

Although ethernet is working on my Optiplex 3020 minitower, I am curious as to why the upper ethernet port LED is solid amber while the lower LED flashes but is also amber?

Is the solid amber indicative of the speed being below Gbit ethernet? Why amber? Amber to me seems to indicate some degraded or problematic state.

Note: this machine has a fresh install of Windows 7 which is currently going through updates. I did install the DELL supplied 'Realtek PCIe GBE Family controllers'

According to the Dell Optiplex 3020 Technical Guidebook, this machine supports Gbit ethernet. Is there any way to set this or verify this value in Windows 7 or the BIOS?

Thanks