I finally built a new computer .  The components should be in my signature.  So far I am loving it.  Went together good and win 8.1 installed without a hitch.
I have a samsung ssd 850 EVO 500g for my C drive
A WD Black 1 TB for my project drive 
a seagate 1 tb for my library ( I plan on replacing that with a WD black)
   I have a few questions.  The power supply is a bottom mount.  I installed it with the fan facing the outside of the case. (sucking air in) Is that a good idea?  I know there are varying opinions on that.
   I am using the stock intel cpu cooler.  so far I haven't overclocked the system.  If I do would I want a better cpu cooler?  When does overclocking really come into play?  When using a lot of soft synths? Running a lot of tracks and plug ins? I am wondering if it's worth my while to spend the time tweaking it.  
    Also are there any other tweaks to make to Win 8.1 for better performance?

Removed... Sorry

Cooling should go in on the bottom and front, out on the top and rear. That does the best job of effectively moving heat out of the case. You want it to work like a chimney, basically.
 
The reason not to do a powersupply drawing in is that PSUs generate heat, so the exhaust can be hot. So you want to have them venting out of the case in general.

I'm sorry I still didn't quite understand you. Should the fan be on the outside of the case so you can see it from the outside? Drawing air in? Or should the fan be on the onside?

Fan inside the case, but mounted so it moves air from the P/S into the room (out of the case immediately). You want the heat from the P/S away from the guts of the computer.

Avoid overclocking like the plague unless you are playing shoot 'em ups.
You've probably got too much power already.
 
The other tweak is upgrading to windows 10 although you might want to wait till next year for better driver support and bug fixes.

mettelus
Fan inside the case, but mounted so it moves air from the P/S into the room (out of the case immediately). You want the heat from the P/S away from the guts of the computer.

This is a bottom mount.  so I don't know if the fan being only an inch from the floor is going to help but maybe there is an option to mount it.  but say there isn't.  You think that it's better to blow out (fan visible from the outside) regardless?  thank you for you input.

There are a bunch of Youtube Vids on installing this PSU: https://www.youtube.com/results?search_query=corsair+rm750+installation that may help.
 
Fortunately for me (being a noob at OC'ing), my MB (a gaming board as well) comes with software (NickShih’s OC Profile) that automatically adjusts all the necessary parameters (raise/lower CPU ratio, voltage, frequency etc...) by simply pushing a button.
If you're a noob at OC'ing, I wouldn't recommend doing this on your own as you can easily fry your CPU or some other components. I also got a 3rd party cooler (Noctua NH-D14) as the stock cooler that came with the 3770k was not up to par. Not sure how good the 4790k coolers are now (probably much better I imagine) and may work out well for you.
Of note, I just set mine at 4.5 GHz and never looked back (now yrs.). For DAW work, you really don't need to OC as this new build is more than enough......if you game a lot, then you may have some research to do (including getting a decent video card).   
 
Overall, you new build looks very nice and should last you awhile.
Good luck!!
 
BTW, if you do game and have a Steam account, I'm Meshodman on Steam........you gotta play TF2 (Team Fortress 2) and best part is it's free!! :))

Thanks!!  Yes I am going to  hold off on overclocking for now for now.  thanks for that link.  From watching those videos it looks like fan on the outside is the consensus

Being mounted outside will not cause issues. Also be sure it is venting into an open space to dissipate the heat.

Being outside just makes it more vulnerable to getting bumped, banged, kicked, etc.