Question Horizontal lines on monitor upon bootup (updating graphic driver doesnt work)

Is this monitor still under warranty? Because if it is, I'd RMA it immediately.

The fact that it goes away, rather than gets worse, when it warms up tells me that something is making a poor connection (Solder point, flatflex connection to the panel, RF circuit) or a faulty capacitor that resolves itself from the thermal expansion when it heats up.

There are of course other possible causes so it would be a good idea to try a different display cable, different graphics card or switch to onboard graphics if your system has an iGPU. Almost certainly not a software issue.

What are your full hardware specifications including CPU, motherboard, memory, graphics card, power supply, monitor model, display cable type, etc.?

How old is the monitor?