Hi there. I have a Lenovo Z50 -75 which has the following problem. When turned on sometimes the laptop will work properly, others will display nothing. I can hear the fun and the hdd but there is no display and no way to make it responsive. I have tried connecting it to a second monitor while in this situation and there is no signal. I have checked both rams and they seem to be ok. Holding the power button to remove electricity residue does not help either. Any suggestions?
If you are connecting the second display while the laptop is on, it may well not show anything. Try the following...
Also note that if the cable is loose or pinched it can also cause the display to work intermittently.
Turn the laptop off (not sleep or hibernate but off).
Connect an external monitor to the laptop.
Turn on the external monitor.
Turn on the laptop.
NOTE: You may have to press an "external monitor" button. Could be the f4 button or a button with two monitors on it, for the external monitor to work.
If you can see fine on the external monitor, then your attached display, or the ribbon cable that connects it, are your problem.
If you can't see on the external monitor at all, or the problem occurs on the external monitor as well, then it is probably the graphics card/GPU that is the problem, which may require the motherboard be replaced.
You may also want to try hitting CTRL + SHIFT + WIN + B to try and reset your graphics driver as another possible fix.
If you can find one that will work with your device it would allow you to use it, but it would use up more resources. If the GPU is not on the motherboard, and is separate internally, it would be wiser to replace it.