CPU Intel Xeon Silver 4114
Mobo Supermicro X11SPi-TF
RAM 3 x CorsairVengeanceLPX16GB(2x8GB)DDR4 2400
PSU Corsair TX550M 550W 80 Plus Gold
Case CoolerMaster MasterCase MC500M E-ATX Case
M.2 Samsung 970 Pro 512GB
SSD 2 x Samsung 860 Evo 1TB
Cooler Noctua NH-U12S DX-3647
Video MSI GeForce GTX 1050 Aero ITX 2G
OS Win 10 Pro
Sound Creative Sound Blaster Audigy FX 5.1 PCIe
PT Pro Tools HD Native (Purchased March 2017)
I/O HD I/O 8X8X8 JPN
Monitor Blackmagic - DeckLink Mini Monitor 4K
Are these the specs of the build? How were the parts chosen? What is the Sound Blaster doing(does the motherboard have no audio)? Have you set Windows( Sound Properties) to use the Sound Blaster as its "default playback device"? Have you updated graphics driver from the nVidia site(not the MSI site)? And removed all the excess crap that nVidia wants to install? Maybe pull the HDN card and see if it looks better(and if it does, then move the HDN car down to another slot). Be aware that the HDN card, though having a short slot connector, it will work in a full-length slot as well
If your friend had not already spent the money, I would have recommended an off-lease HP Z820
BTW, I just re-read and my personal feeling is the 550 watt PSU is maybe too small. I don't recommend anything below 750 watts, these days