Microsoft has confirmed the Surface Book 2 can drain the battery even while charging. It says the battery should never die completely, though this may come at the expense of performance, particularly when gaming.

The problem with the device – which is effectively Microsoft’s take on a MacBook Pro – is that its capabilities require some compromise. It includes a user controlled “Power Mode Slider” for balancing performance and battery life. With this set to full, the main processor draws between 25 and 35 watts, while the graphics processor draws between 70 and 80 watts.

However, while the charger connection could theoretically support 120 watts, the charger only actually passes through 95 watts, which appears to be a design choice to avoid it being too bulky. That means that high-performance tasks such as gaming could require more power than the charger can supply.

Microsoft says that the device is designed so that it won’t drain entirely. This turns out to simply mean that if the battery starts depleting, the performance level will drop back to a sustainable level, overriding the user settings. The Verge, which first noticed the problem, reports that in practice this meant a decline so severe that some titles effectively became unplayable.

To be fair to Microsoft, it hasn’t advertised the Surface Book 2 as a machine specifically dedicated to gaming. However, at $1,500 it’s easy to understand why some buyers might be wary of such a restriction.