Assuming AVR means Automatic Voltage Regulation, this is usually a feature of uninterruptible power supplies (UPS units). This allows them to lower or raise an erratic incoming voltage to the proper output voltage without relying on the batteries; i.e. instead of going to battery if the voltage strays too much, circuits in the unit correct that voltage. This preserves run time for actual outages.
If you are not using a UPS, but a Line Conditioner with AVR, then its output will be more consistently within an expected range. A surge protector alone cannot adjust the incoming voltage that way. How this helps your computer is possibly reducing stress on the PSU. Efficiency drops as input voltage drops, meaning more power is being wasted as heat. Heat is not good for electronic components. A line conditioner with AVR will provide voltages that allow your computer's PSU to operate more efficiently. To see examples of this, read some of the PSU reviews at HardOCP.com, where they include tests at 100V, in addition to the usual 120V tests.