X299 Extreme 4 No POST with multiple CPUs

Hello.
I'm hoping someone could point me in the right direction please.
Two brand new boards with the same issue, so I must be missing something or have something wrong.

X299 Extreme 4, Box label says: Part No 90-MXB690-A0UAYAZ X299 EXTREME4/A/ASRK.
BIOS label says P2.00.
new Intel Core i9-9820X 10-Core 3.3 GHz LGA 2066 165W CD8067304126901 Desktop Processor.
(1)new Kingston 4GB 2666 MHz/PC4-21300 CL19 unbuffered - Non-ECC in DDR4/SlotA1.
new Musetex MU1000 power supply - 24 pin harness to ATXPWR1 port, 8 pin harness to ATX12V1 port(also tried V2 port).
used, known good Nvidia Quadro K600 video card.
new UP1 cooler fan to PWM_CFG1 CPU_FAN1 port.

Board is not mounted in the case, I have it on plastic stand-offs on my table.

When I turn on the power supply, the board LEDs under the heat sink will light solid green, then change to a slow blue flash.
When I jump pins PWRBTN# and GND on the 9-pin PANEL1 header, the cooler fan spins up, the LEDs continue the slow blue flash for 3 or 4 seconds, then the cooler fan and fan in the power supply stop briefly, then the power supply and cooler fan restart. Slow blue flash, reset loop. I get no beeps, and no POST video.

I have tried two brand new boards(thinking the first was DOA), a spare known good i9-7900X CPU, a known good Corsair 1000W power supply, 8 sticks of known good Samsung 16GB 2Rx8 PC4-2666V-UB1-11 RAM in different combinations of slot positions and numbers. I have also tried a brand new Radeon RX580 video card.

Everything I have brings me to the slow blue flash reset loop.

Strangely enough, the actual board layout isn't the same as the drawing in the manual.


Thoughts or suggestions on what I have wrong please?

Thanks for the help so far.

No jumper on the clear CMOS pins. This board also has a push button CMOS clear on the back edge next to the USB ports. Seems odd to me that one could clear CMOS without opening the case, but that another discussion.

- removed everything from the board to start fresh.
- inspected the CPU socket; don't see any unusual pins, at least what my old eyes can see with a magnifier ;)
- gently re-installed the i9-9820x CPU.
- re-installed the cooler with just enough tension on the screws so the cooler doesn't slide around.
- new RAM in slot A2
- 24 pin power, 8 pin power to ATX1 port
- turn on power supply, board LED turns blue, then changes to slow blue blink.
- jump power switch connectors on header
- cooler fan spins up, board LED continues slow blue blink.
- approximately 15 seconds the cooler fan stops, the blue blink stops, power supply fan stops, and power supply 'clicks'.
- a second or two later the cooler fan restarts, the blue blink starts, and the power supply fan starts.
loop, loop, loop, loop.
I walked away and left it for 15 minutes.

Just for the heck of it I tried the known good, used i9-7900x extra CPU I have. With this one, the fans spin up, the slow blue blink starts and nothing else happens. No restart loop, just the steady blue blink. Also left that for about 15 minutes.

Thanks.

- The BIOS sticker "says" P2.00.
- This is actually the second brand new board I have tried, both with the same symptoms.

I'll have to dig around in the parts boxes and see if there is some kind of PC speaker I might have...