So on top of my gaming rig i'm also planning on building a media server.
This will be running plex and should be able to transcode multiple 1080p streams simultaneously
This is what i've got so far, What do u guys think?

PCPartPicker part list / Price breakdown by merchant

CPU: Intel Core i7-4790K 4.0GHz Quad-Core Processor ($324.99 @ SuperBiiz)
Motherboard: ASRock H97M PRO4 Micro ATX LGA1150 Motherboard ($73.98 @ Newegg)
Memory: Crucial Ballistix Sport 8GB (2 x 4GB) DDR3-1600 Memory ($56.99 @ Adorama)
Storage: Seagate Barracuda 2TB 3.5" 7200RPM Internal Hard Drive ($71.99 @ NCIX US)
Case: Sentey SS1-2422 Plus (@49.99 @ Amazon)

Total: $577.94
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-03-30 08:51 EDT-0400

get more harddisks, you'll probably fill this single disk quite fast.

I have 16TB of externals to hook up to it

thats an argument ^^

i'd probably get a small disk as "boot drive", to have it independent from the data drive.

makes it a bit easier to manage and you have less risk when messing around with the system.
(you can safely reinstall OSes, and if they break you dont lose your data)

Looks good. But if you have 16TB hooked up externally, ditch the spindle internal drive and just use something like a 128-256gb SSD. Since it's a server, you probably won't need more than that and you won't need to load it up with a ton of applications, not to mention temp storage on it from transcoding will get a huge boost in performance. Maybe double the memory since memory is usually a cheap and easy upgrade. At that point, you could disable the page file, forcing everything to run from RAM and get another huge performance boost. Since there isn't much volatility on that system (just the externals I'm guessing), you wouldn't need to worry about any sudden power loss or similar.

Everything looks good to me. I run Plex on my main system and the CPU is a 3770k and is able to transcode multiple 1080p streams without issue. So you definitely have more than enough power, even with what you have picked out right there.

Actually, now that I think of it, that board looks very similar to mine as well.

ended up getting a 128gig ssd and a 2tb spin just for aditional storage also a 4790 instead if 4790k since no need to OC

Might be a bit late but I would recommend setting up a raid array for your HDDs for redundancy.