Microsoft has unveiled the Surface Book few time ago, but didn’t provide much details about the discrete GPU (we only know that it is produced by NVIDIA and comes with 1GB of GDDR5 memory).
Some users have had the opportunity to run the latest GPU-Z 0.8.5 on a Surface Book and here is the screenshot:
This GPU-Z screenshot reveals the GPU device ID: 0x134B. This GPU is currently unknown but belongs to the same family (Maxwell architecture) than the GeForce GT 940M (device ID: 0x1347) or the GT 930M (0x1346). And with 384 CUDA cores, the mysterious GPU shares the same DNA than the GT 940M.