Computer doesn't respond when pressing power button, first time builder.

Congrats on your build. I've built a few over the years and every time the tech has changed so much, it took days of research, waiting for parts, learning curve for installs, reading hundreds of misleading blog entries, finding those very few knowledgeable folks who can actually help and then trying to turn it on. Trying to turn it on is the most nerve wracking part. My last challenge was setting up the bios for the new ssd, installing the os and then finding out that storing info to the 4T hdd is not simple either. Gotta remember to manually route stuff to the hdd, cause by default, it all goes to and crowds out the ssd. Last I checked, the only solution to that was to buy a huge expensive ssd and only use the hdd for backup. I just figured out to oc the 4770r cpu and tweak the volts on my ram. Should of also bought all new fans that connected directly to my gaming mb for auto temp control. I bought a bunch that connected normally and don't have the ability to vary the speeds. I got lucky with the nice huge be quite cpu fan as it was designed to plug into the mb and has auto control.
Sometimes turning it on is just the start of the challenges. I'm neve really sure of how I've actually done it at the end. Then I pray for a stable system (like is the psu big enough...) lol
 
By the way, using a mass hdd is tough too. If you put the os on ot, windows will not see more than 2T. Of course you can download formatting software so the system sees it, but it uses the extra space as an additional vital drive with its own drive letter (not good). But if you use an ssd for the os, and the hdd for data only, the os will format it differently and you get the 3 tire storage space on one drive letter. But remember, you must manually load data (files, games, etc) separately and manually to get them on it. Of course my kids don't do that and the ssd is getting crowded fast (tried to save $ by getting a ssd just big enough for os).