This is my first time building a pc and I followed an online tutorial and also looked over all the manuals and I'm sure everything is mostly plugged in right. The fans are turning on and everything when I start my computer but my monitor is saying "no signal". Also on my motherboard there are 4 led's that say: cpu, dram, vga, boot and when I turn my computer on the cpu and vga led's go red and then go off?? Can anyone help?