I had the same issue. But it somehow resolved itself (or after accidently changing something). I have no clue how tho. Look through all your settings and tell what you might have enabled or disabled.
Some of my settings under Video > Plugin settings:
Shader Configuration with FXAA enabled and Shade Boost enabled with Saturation on 45. TV shader NONE.
Hardware mode settings: Allow 8bit OFF (I think this would be best for your 4790k), ... Ill just post some screenshots
http://prntscr.com/e9ethr http://prntscr.com/e9etp9
I also switched back to the old GSDX plugin driver as he doesn't mention it here. (OP prompted to download and install a new GSDX in the old tutorial) http://prntscr.com/e9eufq
And GSWindow settings: http://prntscr.com/e9euy9
Some of my settings under Video > Plugin settings:
Shader Configuration with FXAA enabled and Shade Boost enabled with Saturation on 45. TV shader NONE.
Hardware mode settings: Allow 8bit OFF (I think this would be best for your 4790k), ... Ill just post some screenshots
http://prntscr.com/e9ethr http://prntscr.com/e9etp9
I also switched back to the old GSDX plugin driver as he doesn't mention it here. (OP prompted to download and install a new GSDX in the old tutorial) http://prntscr.com/e9eufq
And GSWindow settings: http://prntscr.com/e9euy9