Tom Warren, writing for The Verge:

One issue I did run into with the Surface Book 2 is the power supply. Microsoft has only supplied a 102-watt charger with a machine that has an Nvidia GTX 1060 inside. Most similar laptops are gaming ones that have 150-watt or even 200-watt power supplies. There are two batteries inside the Surface Book 2, one in the base and one in the tablet portion (screen) itself. The base battery discharges too quickly with the supplied charger, meaning the Nvidia card (located in the base) will disconnect in the middle of a long gaming session at maximum performance even if you’re plugged in.

Microsoft is currently investigating this issue, and believes I have a faulty power supply. The company says the “Surface Book 2 is designed to supply enough power to maintain and charge, even under heavy load (including gaming).” I didn’t notice the discharge with apps that rely on the GPU, but most productivity apps simply use graphics power in short bursts rather than long periods like in games. I suspect the 102-watt charger isn’t enough for full performance gaming sessions, which will disappoint many who were hoping to use this as a gaming laptop alongside work tasks. I’ll update this review if the replacement charger makes a difference.

I have also tested with an old 65-watt Surface Book charger and the base still drains too quickly during gaming. I’ve also tested with a Surface Dock, rated at around 90 watts, and this still doesn’t hold the base charge to keep up while gaming. In all scenarios I also tested with the recommended “best battery life” setting, but the base still failed to charge properly during heavy gaming loads. If a replacement charger doesn’t work, Microsoft could potentially fix this in software by reducing the GTX 1060 clock speeds further and slowing the machine down.

Or… you know… they could just supply a more powerful charger.