Maximus X Hero

Hello community, I am building a pc with Maximus X Hero mobo. It only has 1 x ARGB header ( 5volt) and I have 3 to connect. Just wondering, is it safe to add 3 of them into the header using a splitter? The splitter I have is this one: https://www.newegg.ca/p/13K-0005-000B1?Item=9SIADDZ7Z51379...

So, yesterday morning I installed a brand new i9-9900K on my Z370 ROG MAXIMUS X HERO and since yesterday late evening I noticed a slight coil whine noise coming out from my motherboard's VRMs. It's not from any fan clicking or anything, it's not from the GPU, since I'm on idle, it's not from...