I have two DN2800MT (latest BIOS ver 0165) motherboards with internal power, they are built in a 1U rack case side by side. I have connected from the back-USB port to keyboard/mouse to an BlackBox ServeSwitch EC Series DVI KVM switch (16 port).
The KVM keyboard is not recognized during POST, eg when the BIOS settings is coming up and before the OS is loaded (in this case windows). So if I want to enter BIOS it is not possible, or selecting in the startup menu (windows) the keyboard is not responsive either. So in this case if I have the KVM keyboard connected to any of the back-USB ports it is not recognized in any cases before OS is loaded. (It is recognized properly after windows is loaded).
But, If I connect normal USB keyboard to the back-USB port, I have no issues in POST or in startup menu before any OS is loaded. So in this case it would think that there is something with the KVM switch.
But, If I connect the KVM switch keyboard/mouse USB cable to the front-USB of the DN2800MT, it works in POST and startup menu before OS is loaded, and this is consistent behavior. I can go to BIOS and then switch between front and back USB ports and I will each time get same behavior, not working with back-USB, and working with front-USB.
When I was in contact with BlackBox they did mention following;
"Another issue has been when the USB port on the motherboard has slightly inconsistent USB power and the KVM does not recognise the presence of USB devices. Change the USB port on the CPU that the KVM is connected to. The USB ports that are on the rear of a CPU are integral to the motherboard and share power w/ ethernet, vga, etc. If the CPU has USB ports in the front - try using those as they sit on a daughter card and do not share power with."
I don't know if it is true that there are power inconsistency on the back-USB, but thanks to this tip I tested the front-USB port, as I never thought there would be any difference between the back and front USB ports.
There are couple of other USB related issued with DN2800MT on the forum;
These could be related as well, but there is no information if they used front or back USB port.
What difference are there between the back-USB and front-USB? why does these ports behave differently? Anyone else noted the same?
DN2800MT, BQMT216002PD AA G23738-800, BIOS ver 0165
DN2800MT, BQMT2140036M AA G23738-800, BIOS ver 0165