Thank for the reply.From the MB manual page 15, the MB has the 4-pin RGB header (12V/G/R/B), and it can support up to 2m, or 2 Amp strip. https://www.gigabyte.com/Motherboard/X470-AORUS-ULTRA-GAMING-rev-10#support-manual
But I can't find the info for the Phanteks strip from the case manual, it only shows the strip is 300mm, but from the picture it has 4 wires, hope it is the same +12V/G/R/B header. If it is, then you are fine, otherwise you may need the adapter or the RGB controller.
http://www.phanteks.com/Eclipse-P400-TemperedGlass.html