My system was running fine till yesterday. Today, when I started, there was no display but computer is running. Checked hdmi cable. Opened cabinet, saw gpu fan spinning on and off. Vga through mobo was displaying. Tried reseating gpu, ram, checking pci cables. Didn't worked. Still, gpu spins on and off. Now, computer is in a 'booting up and shutting down' loop. Kindly give suggestions. Thanks. I5 4440, GIGABYTE b85m-d3v-a, gtx 970, corsair vs550.