USB not working on Dell Optiplex 320, 745 and 755

[oJAsVI]

Hello friends, i am having the Dell Optiplex 320 and also worked on Dell Optiplex 745 and 755 and founded that USB is not working on these systems, i am not getting any response about it response from the keyboard and mouse, even the interactive whiteboard is not responding. It is been important for me, as it been used daily. Even try to plugging it properly then also it has not worked for me. I have observe the same thing is been happening on Dell D531 and D630 laptops also. Does anyone else has got the problem which i am getting and also what is the problem. Please suggest me some solution for it. Thank you.

[Gaganvihari]

I have replaced the motherboard of Dell Optiplex 745, and i am not getting any sort of the problem with it, i have got the same motherboard which was there on the board. So i have not come across with the problem.

[JoanaJhon]

I would suggest you better unchecked all the USB Root Hubs power saving and also do not allow the USB to come back to save power, so you better allow the USB to be wake from the bios and if that does not work then you can call up the Dell Customer care they might be able to come and find the solution to solve the problem and you might be able to get the reason for it.