I've worked fine with this build for over a month. But recently, the monitor would turn off and say "No Signal" and the mouse and keyboard would stop lighting up. I would try turning my computer off and turning it back on but the keyboard, mouse, and screen still wont respond. I also dont hear the fans going on. So I had to resort to reseating the CMOS battery and everything would work again. Today the same thing happened again. So I reseated the battery and everything would work. Whats going on? Would it help to flash the BIOS? All of the parts were bought new if that helps.
If you have no problem with the PC prior to Windows starting, updating the BIOS may fix your issues. Try this first.
Re-seating the batteries in any device sometimes gives you brief functionality that doesn't last. I'd pick up a new battery to ensure it's not just an issue with the battery.
If neither of those work, I'd try running the PC with no video card using on-board video and see if you still experience the issues. If you don't, you may have an issue with the video card. If you still get issues, then you could test the PSU. Testers run around $30 and are good to have on hand. This is good to do prior to building anyhow, since a power problem affects everything.
If the PSU checks out, you could have a power problem with one of the disks and so on...
Try the things at the top of the list. Update the BIOS. Often this is all that is required.