So I just built my second system and right at the very end of the whole build this happens.. I install the OS and the Motherboard Drivers (Chipset Etc..). Then I turn my attention to the graphics card as i move onto update its drivers, I install them and as instructed restart the machine however when the machine reboots my monitor receives no signal. I then decide to revert to the motherboard graphics by taking out the card and try to install drivers for my network card to download the latest graphics ones online. Then I get the problem of the machine unable to detect the Wireless adapter properly as some times it appears in my device management center and then after a while disappears.
Take out the RAM sticks, start the PC, and listen for beeping sound from MB, if it beeps then the MB is probably ok, if it doesn't then the MB is faulty. But this test will not tell you for faulty PCI or PCI-E slots.
Try the GPU and NIC on another system to isolate the faulty part. If those components work on a different system then there is something wrong with your MB's slots. And what is the make/model of PSU ?
You can try with a single stick of RAM, and interchange it, see how it works.