Yes, it's generally fine to use mismatched DDR3L and DDR3 RAM.
Yes, it's generally fine to use mismatched DDR3L and DDR3 RAM.
It seems the device won't upload because it can't supply enough voltage for DDR3.
It differs depending on the system. Just insert it and check if it functions. If it works, that's good. If not, send back and get a DDR3L stick.
It could function, or at least my ThinkPad T440p operates smoothly with mixed DDR3L (1.35V) 8GB and DDR3 (1.5V) 4GB modules. However, it likely hinges on whether the 1.5V module can maintain stability at 1.35V or if the device supports that voltage level