I have 2 SSDs in RAID0 and Windows loads lightning fast but POST take ages. And there is that ugly "RAID page". I can live with long POST, before I had much slower PC, but this RAID thing is really disturbing. Is there anything that I can do about it?
Here`s a video with it:
https: //youtu.be/6HoHuvCzOwo
And my BIOS settings of SATA controller and BOOT:
http: //imgur.com/a/3EKz3

I would suggest going with a Intel 750 series PCIe NVMe SSD. Probably faster than your raid setup.

Verbose of ANY RAID setup is part of the specification (no matter chipset controller or AIC). Personally I wouldn't have it any other way. Last thing you need is failed array and 0 knowledge about it, until you see 'no system drive found'.  There is no such thing as limited verbose or quiet mode during POST unless controller provide such function (usually found only on some most modern RAID cards and only in limited capacity to prevent full silent mode). It's most low-level access imaginable. By definition RAID is Legacy solution not bound by UEFI rubbish and because of that command prompt is visible. 
 
BTW: Just watched video. Man that's blink of the eye. Like 2 seconds at most.  Expected that it loads at least half as long as full blown RAID controller (depending on a model and configuration 50-90 seconds) or something. Don't take it the wrong way, please. IMHO most current, young generation of PC users is not patient enough. For me lack of verbose in UEFI configurations and these pointless full screen logos (at east logo can be disabled) are biggest fail of all; for you 2 seconds of 'dos prompt' it's biggest drawback. How much technology has changed in the past 30 years. Almost unbelievable.
 
I fully agree with going with single SSD. It will eliminate prompt for starters. System will load just as fast. It's not like RAID0 offers any tangible benefits - especially when compared to even most slow of NVMe drives - while increasing overhead and search time on deeper queues.