FWIW, my HD playback graphics card is 500Mb and works perfectly, so for 4K that suggests about 2Gb anything more and you are into 3D / Gaming graphics which Renders as you play. Sadly this takes a lot of computing power and often these Graphic cards will have their own power lead to the PSU, - this needs to be capable of delivering the additional power. Additional power generates more heat.
I thought OP had said he's not using 4K, so even a 2Gb Graphics card is excessive IMHO, - but Whatdoiknow...
Nice Spec BTW, - excepting that PSU-rating.... might struggle...? Also, for a small amount extra push the 1st HDD above 1Tb since this will normally hold all the clips, with the second storing rendered stuff. FWIW My last HDD was 4Tb - you can't have too much storage and make sure the MBO has spare SATA connectors should you want to add another drive. [ an External drive is worthwhile, since you can store work separately (kept safely), if/when you are away.].
Cheers.
The PSU is 50w higher than the makers suggestion, seems to be fine after a couple of months use.