Hello, I have had this problem on my y40-70. This is caused by changes to the locked bios. The bios has 2 modes, one for OEM and one for end users. The one for the OEM can seriously affect thing such as the graphics. This caused the flickering for me when using high-end graphics on battery. This issue can be resolved by simply upgrading the BIOS. If there is no update available, and you cannot flash the BIOS, clear the CMOS (on a desktop machine this is done by the CMOS jumper, but on a laptop its different). YOu have to open up the computer, and since your model is the y50, it is done by removing the screws on the bottom and prying the back cover off. Then you have to remove the main battery (look up lenovo y50 hardware manual), and the button cell battery that is attached with a red and black twisted wire (just pull from the wire). After doing so, you need to let the capacitors discharge by waiting approx. 10 minutes. After doing so, reattach the batteries (the CMOS and the main) and reboot the machine into the BIOS screen (using the onekey button). Set the date and time (as reseting the CMOS resets the date and time) and VOILA, your problem is fixed!