P.S. I see that you're using 3rd party PSU cables in your build. So if i et some quality cables than i can replace stock ones?
Yes, you can use custom sleeved power cables in place of stock power cables.
My custom sleeved power cables are CableMod ones. Namely their ModFlex full cable kit.
E.g Skylake build has this kit:
https://cablemod.com/product/cablemod-se-series-xp2-km3-cable-kit-red/
Haswell build has this kit:
https://cablemod.com/product/cablemod-se-series-xp2-km3-cable-kit-blue/
And AMD build has this kit:
https://cablemod.com/product/cablemod-se-series-xp2-km3-cable-kit-green/
Since cable kits are specific to each PSU brand, you
have to have compatible kit of your PSU!
Sadly, CableMod doesn't have ready made kits for NZXT PSUs (NZXT is relatively small brand in PSU scene). And with this, you either need to use cable configurator,
Expand NZXT here:
https://cablemod.com/compatibility/
Or better yet, i suggest that you send CableMod an email and ask them directly how to get custom sleeved power cables for your C1500 unit. I'm sure CableMod can guide you through the process. That is, IF you want to go with CableMod.
Another option would be contacting NZXT and asking them which brand custom sleeved power cable kits they suggest, since CableMod isn't the only brand. Albeit, CableMod is best known/highest quality.
When i was looking for CableMod custom sleeved power cables, before purchase, i contacted Seasonic and asked Seasonic about CableMod cables. Seasonic said that CableMod uses equally good cables to their own stock power cables and i was fine using CableMod cables. So, that's what i did.
Edit:
Cheaper option would be using power cable extensions, that you clip to the current power cables, extending the power cable. When using PSU shroud, you can have the stock power cables hidden under there but once the power cable comes out of MoBo tray into the view, you can have cable extension there, for nicer eyecandy.
CableMod offers plenty of cable extensions,
link:
https://cablemod.com/product-category/pro-series/pro-extension-kits/
With extensions, it doesn't matter which PSU you have, since other end of the power cable (where extension clicks into), is same across all PSUs. It's just matter of picking out the right color pattern, or if you like, you can even make custom extension cables within cable configurator,
link:
https://store.cablemod.com/configurator/
Changing extension cables length, color (by individual wire) and other features (e.g cable combs).