Not All Beep Codes Signal an Error for Intel® Server Board S5500/S5520 Families
Intel® Server Board S5500/S5520 families are designed to indicate USB readiness by a series of beep codes early during POST, just before video becomes available. These 4-5 beeps mean that USB is powered and initialized, in order for USB devices such as keyboard and mouse to become operational.
If a USB device such as a pen drive or USB CD/DVD ROM drive is attached to any external USB port, a beep code means that the device is recognized, powered and initialized. Each USB port will issue a beep once an external device is ready for use.
These beep codes do not signal any errors, they are by design to advise the user of USB readiness during POST and when attaching external devices.