The high performance card (1050 for 13 inch, 1060 for 15 inch) is in the keyboard base.
You may be interested in this brilliant feature: If you wish the keyboard to be out of the way, you may be interested to know that the keyboard can be turned around backwards, and the unit can be operated open or closed, including closed with screen facing out instead of towards the keyboard. Very handy for full power-user/gamer use with wireless or gaming keyboards and controllers, while getting full graphics and charging.
I have another question because I read in a review that the system's GeForce GTX 1060 is only enabled when on mains power, so don't expect anywhere near the same performance playing on battery.
So, this means that also working in photoshop for example on battery, means that GEForceGTX will be disabled??
I use the GeForce GTX 1060 on my (two) Surface Book 15 inch computers without mains power. The information you read is not correct.
As a test, I just now verified that Corel PaintShop Pro X9 64-bit is set to run using the High Performance NVIDIA graphics. I launched it on battery power. Runs perfectly. Then, if I try to eject the screen (Clipboard), I got a message that Corel PaintShop Pro X9 must be closed first. This is fully expected. Then, I closed PaintShop, ejected the Clipboard, connected it reversed, and started PaintShop again.