Well shieet... It always take JR to make me come to my senses
Really, not the fact that common sense should dictate that 'I don't really need this, therefore i should spent my disposable income on maybe trying more graphics cards because I like the colour'
X99 is a proper power house chipset, i know there are instances where people use it for gaming but thats due to the limitation of the PCI lanes on the mainstream platform so running tri-sli/crossfire etc
Now you say you want to play with 3D modelling and video rendering, let me put this into perspective, I mess about with a lot of videos for our gaming nights, Im talking 100's of GB's
(i dont post most of them because X Rated :lol my 4790K at 4.8GHz chucks out 1080p like its nothing, hell my 3770K and the 2700K still do well with rendering, Wraith made me a 3D wallpaper which I rendered because i wanted to see how my system performed and with 50,000 particles it didn't do so bad.
The 4790K has more than enough grunt to cope with what you want, I could right now drop money on a baller X99 setup or badass Skylake setup, but the cost would outweigh the performance gain by a massive margin, if the situation ever arose where my paycheck depending on the processes then X99 all the way as time is money, but is saving 9 minutes rendering a 1080p gameplay video really worth the ~£1500 cost to go X99?
But I personally think you should have a play with your current setup maybe get a few graphics card to kill some time, and see if you can actually reach the limitations of your hardware, before wanting to go X99.
P.S The ASRock is a #baller motherboard 
