My system won't boot. It's a minimal test-bench configuration: z490 Strix E-Gaming, 10600K, one 8-GB stick of DRAM in slot 2, monitor hooked up by HDMI to motherboard, keyboard connected. The power supply is a Seasonic Prime 1000W. This is a new build. I've built 2 computers before; I have basic competency.
On startup the process hangs before video output. The Q-LED for "Boot" is lit up; no other Q-LEDs are lit. The Q-Code is A2: "IDE Detect".
I don't have another system with a compatible cpu socket or RAM slots, so I can't independently test those components, but neither diagnosis system on the z490 suggests either one is a problem.
EDIT: I've long advised other people to take a break from any task that seems unsolveable, then come back to it later. Giving your mind a chance to rest and let ideas slowly bubble to the top often brings insight. So that's what I did. And it worked.
The "Boot" light was on because there was no bootable device installed. I knew that, that was intentional. I just wanted to get to BIOS and confirm that the core components were working before building out the whole system. I thought the "Boot" light indicated a failure to POST. But I realized it might not. The light might go on even when POST succeeds. Maybe, I thought, the system was passing POST but had no video signal. And maybe the Post Code just indicated that the system was looking everywhere for a boot device. The keyboard I had connected had no caps-lock indicator light, so I switched it out to one that did. Pressing caps lock lit the indicator light, proving that the system had passed POST. Eureka.
The monitor I used to test the core components is an old one. Last time it was connected it was to an old system, by DVI. And the monitor was not able to automatically detect input signals: it had to be manually switched to use the HDMI cable that was connected now. Another Eureka. All is good now.