Overruns occur when the internal First In, First Out (FIFO) buffer of the chip is full, but is still trying to handle incoming traffic.
Data from the network will be received into the buffer, whereupon the chip will attempt to move the data from the buffer to the router's shared memory for the CPU to process. If the chip is not able to move the data from its internal FIFO buffer into shared memory faster than the rate at which data is received on the interface, then the internal FIFO buffer will be full, incoming data will be dropped, and the overrun counter will be incremented.
Try to replace the cable between the Server and switchport and also try to hardcore the Speed and duplex.
regards,
-amit singh
