I was having this problem as well, but seemed to have solved it in a really weird way. The laptop, that I use for 95% of my work, has a 540m and an Intel 3000HD. I have a shortcut to the editor and instead of launching it with the 540m, I launch it with the integrated card. UE will still make it force the 540m(confirmed within the logs and Nvidia GPU Activity), but it seems to alleviate my problems. In the logs, it will show that the Intel card is only DX10, so I presume that it’s forcing the Nvidia card because it has DX11.
I had been getting BSODs with the watchdog error just trying to open the project browser. I was also getting random crashes with the material editor. Haven’t had one since I started booting UE with the integrated card.
Again, this is a really strange workaround and I can’t exactly explain why it works, but it works and it’s definitely using the 540m…