Processor: AMD A8-3870K 3.0GHz Quad-Core
Motherboard: Gigabyte GA-A55M-DS2 Micro ATX FM1
RAM: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1866
Case/PSU: Apevia X-TRPJR-BK/450 ATX Mid Tower w/450W Power Supply
So, every thing came in today so I sat down and put it all together. Used the HDD from my previous tower, DVD drive, and I CAN use my previous GT 9400 nvidia GPU but I bought the processor for the integrated graphics.
The problem I'm having is everything turns on, but no signal goes to the monitor by either the mobo VGA or the GPU VGA. I haven't ever actually overhauled like this before, so I'm not sure if there is something special I need to do to get the signal to work.
Reset the BIOS manually by removing all power sources (power cord, monitor, and powered speakers). The press the power button to discharge any residual power (seriously). Remove the battery from the motherboard. Wait a couple minutes and then reverse everything. DO NOT install the 9400. Only connect to your on-board video. You should see a display upon booting.
If not, re-install the 9400 and verify that the on-board video is enabled and the primary video device in the BIOS. If not, make it so. Save. and shut the system down in order to remove the 9400 and try again.
Assuming the parts are in working order and they should be since you bought new items the most logical thing would be to change the DVI, VGA or HDMI cable you're using since it may be damaged. The other thing I would check would be the PSU. Make sure the 24-pin mobo cable and the 8-pin cpu cable are properly seated on their position, or try another PSU if you have one.
Also.. I'm not questioning your intelligence in any way but... make sure your monitor is actually on. I've done simpler mistakes that have drove me crazy.