iMac shows a distorted blank/rainbow pixel screen after turning it on
iMac works when I press the shift key during start up, which then opens in Safe mode, but during a normal startup, after the apple logo disappears and leads to the login page, instead of the log-in page, a half blank white screen, with rainbow pixels distort half of the blank screen. The iMac works as expected during safe mode as the login page appears, seems normal as well as the desktop after login.