I just got a new tower for my cpu, I put everything in it, and tried turning it on, but when I try, the monitor light just keeps blinking. We tried 2 different monitors, but it still happened, so it's not the monitor. I tried a WORKING GFX card, and the integrated one, but it still blinks, and nothing shows up. I tried changing the red switch in the back from 115 watts, to 230 watts, but that didn't do anything either. When I plug in a USB mouse, the laser doesn't show up, but when I plug in an older one, that isn't USB, that one does work, and the laser does show up. (The USB mouse is BRAND new) When we turn on the Cpu, the hard-drive makes it's normal sounds, but gets to a certain point, and then restarts, and just keeps doing that. So we tried my brothers, working hard-drive from his CPU, and it doesn't make that noise, but the monitor still stays blinking, and a black, blank screen. The top left prong on the north-bridge or w.e is bent also. We tried using 2 different prossesers, and neither one fixed the problem. Every part in the CPU, is brand-new. Except the RAM.
This all makes me so mad, because my old cpu had been broke for like 6 months, and now I finally get new everything, and it STILL, doesn't work!! ARGH!!
PLEASE, PLEASE, SOMEONE, HELP. I beg you, I REALLY want my CPU fixed =[

It could be a bad power supply, or a bad motherboard. Did you use the standoffs when you installed the motherboard in the new tower, it could be shorting out.

Make sure your hard drive & ram is ABSOLUTELY CLEAR, put in the disk for your OS, then select the drive from a list, check your BIOS, make sure all drivers are installed right, i'm not really sure what the problem would be, sry.