I stay away from efest. They're re-wraps or seconds from name brands.
The Smoke X-Cube II has built-in thermal protection. If the board gets too hot it will shut down until the temperature drops to an acceptable level. Upgrade the firmware in your X-Cube, if you have not already done so. It will go up to 180W with revision 1.093. I had problems with a version of the firmware updater. Let me know if you encounter any and I'll send you a link to a working version. Back up your apps, and don't let Smok automatically update them. Version 2.5 for Android crashed on launch. My Android tablet would not run the app as it was not Bluetooth 4.0 capable. It would pair with the X-Cube, just not communicate. I spent $150CDN to get an iPhone 5s as a remote for it. I'm impressed with the electronics, and not so much with the firmware and apps. The case leaves something to be desired, as the firing bar is a pinch point on three of its sides, and sticks regularly. The device is very promising, but like much in the vaping world was rushed to release.