Hi sherryzxt,

If the monitor has driver’s disc, please install the drivers for the monitor.

If you do not have the disk please use this link to install the drivers for the U2312HM monitor: http://dell.to/10iWvkw

Click the above link, select the operating system, click Download file and install the drivers listed by following the onscreen instructions.

Try changing the input source depending on cable connected, by using the monitors “Onscreen display menu”. Refer this link: http://bit.ly/Wjj0eg

Kindly let me now the results.