Steel Legend x570 - No POST or BIOS

Many thanks up front for taking the time to read this and any assistance is greatly appreciated.

Issue:

I have breadboarded the MB, CPU, RAM, GPU, HDD, and USB boot stick; however, the MB does not POST and does not display the BIOS (or anything) to the display. There are 4 POST status indicator lights for the Steel Legend x570 motherboard (CPU, RAM, VGA, and BOOT), and upon first power-on the lights cycle as expected and eventually the VGA and BOOT lights remain lit. After adding a speaker to the MB, the beep code pattern that results is: 3 beeps, pause (about 1 second), 3 beeps, and no more beeps occur (e.g., no continuous beep pattern).

Components:

MB: ASRock x570 Steel Legend WiFi ax

CPU: AMD Ryzen 7 3800X - (Also tried: AMD Ryzen 7 2700X)

RAM: G.Skill TridentZ RGB 32GB (2x16GB) 3200 MHz - (Also tried: Corsair Vengeance Pro RGB 64GB (4x16GB) 2933 MHz and Patriot Viper Gaming RGB 16GB (2x8GB) 3200 MHz)

GPU: Zotac GeForce GTX 1060 DirectX 12 ZT-P10620A-10M 6GB 192-Bit GDDR5X PCI Express 3.0 - (Also tried: ZOTAC GeForce GT 730 DirectX 12 ZT-71115-20L 4GB 64-Bit DDR3 PCI Express 2.0)

HDD: Samsung 750 EVO 500GB

BOOT: Windows 10 Pro USB Stick

MONITOR: Dell Ultra P2715Q - (Also tried: TV via HDMI)

Component Installation:

1. CPU is seated within the socket. Heatsink/fan installed with thermal paste. CPU seating checked and verified.

2. RAM is installed in A2/B2, per MB documentation. RAM seating has been checked and verified.

3. GPU is installed in PCI slot 4.

4. HDD is connected to SATA0.

5. MB maintains an 8+4 pin CPU power connector. CPU power is provided by 8 (4+4) pin PS cable. Alternate 4 pin connector on MB remains unplugged.

6. ATX power is connected to MB.

7. MB speaker is connected for beep code reference.

8. SATA power applied to HDD from PS.

9. Monitor connected to GPU HDMI/DP connector(s).

Troubleshooting:

CPU: I have tried both a 2700X and 3800X CPU. I have ensured the CPU is seated correctly with no bent pins. Result using either CPU remains unchanged.

RAM: I have tried multiple manufacturers and frequencies for RAM. I have also tried using a single stick in each slot. Result remains unchanged.

CMOS: I have removed the CMOS battery and shorted the CMOS reset pins upon any component level change. Result remains unchanged.

GPU: I have removed the GPU and attempted to power. Beep code changes to 5 long beeps, which illustrates the MB cannot detect a graphics card as expected when using the X-series Ryzen CPU. Reinstalling the GPU and powering the MB results in the original beep code pattern: 3 beeps, pause (about 1 second), 3 beeps, and no more beeps occur (e.g., no continuous beep pattern).

MB: I RMA'd the original MB I received, as I believed the MB was faulty. However, both the original and replacement MB behave in the same fashion with the same beep code pattern.

BOOT: I have tried plugging the USB boot stick into the MB for initial power on to see if the BOOT indicator light will go away, but it remains lit. I have verified that the USB stick is bootable on a separate computer.

Basically, I have tried everything that I can think of to correct this issue, and nothing seems to work. The CPU and RAM are compatible according to vendor's websites. If anyone has experienced anything similar or has any insight, some guidance would be greatly appreciated. Thank you very much.

Thanks for the suggestion. PCI slot 1 is currently obstructed by the CPU heatsink/fan, which I will have to replace with the stock CPU heatsink and test it out.

Same motherboard, (with ryzen 3600 and rtx 2070 super), same problem but with an initial fast beep followed by other three always fast.
Tomorrow morning I'll try to change the PCI slot, I hope it's just that, but it's also true that I have bought some ram not compatible with the motherboard (Steel Legend 3600 mhz).
Tomorrow morning I'll update.

Posting this for those who are also looking this issue up.

I have a GTX 1080 Ti and had this problem, also I DO have it in PCI 1. What I did to fix it is plug my monitor in the FIRST Display port slot (the very left slot) I guess the motherboard just posts to whatever is in the first slot. I had my Valve Index in there which is why I didnt have my monitor there.

Hope that helps someone who pulled this forum post up on google!