GPU's led turn on but the fan don t spin and the monitor dosen t detect the PC .For a few months, the PC that I assembled a few years ago, when I turn it on most of the time the monitor does not detect it, so in order to use it I have to turn off the PC, open the case, disconnect the GPU (RX 590 sapphire ) and plug it back in and try again until the monitor detects the PC. I can't even use the CPU's integrated video card to determine that the GPU is really the problem, because it doesn't have it (r5 2600x). I also checked that it's not the monitor using the PS4 several times, and I also changed the HDMI cable. Maybe the problem could be the power supply (Corsair TX650M). Also the PCIe connection of the motherboard (Asus Prime B-450 plus) could be. I don't know what to think anymore.