[SOLVED] No POST on Asus WS-X570-ACE - strange LED behavior

May 17, 2021
I'm upgrading the CPU, RAM, and motherboard on my computer, with these parts:
  • a Ryzen 5950X CPU
  • 2x KSM32ED8/32ME Kingston 32 GB unregistered ECC RAM
  • an Asus WS X570-ACE motherboard
  • an M.2 SSD (Samsung 980 Pro 1 TB)
Furthermore, I already have:
  • a GTX 1080 Ti GPU
  • 650W power supply (Cooler Master V650)
  • 7 SATA units (disks, SSDs, etc.)
  • an NH-D15 cooler (got a NM-AM4 bracket kit to use it on the new system)
The red LAN2_IN1 LED lights up on the motherboard when it's powered, but turns off after a while (whether the computer is turned on or just connected to power). When I turn the computer on, the yellow DRAM Q-LED lights up for a few seconds, then turns off. Nothing happens after this; there's no video out through either the integrated or GPU DP ports. The CPU and case fans run until I turn the computer off again (by holding the power switch; just pressing it doesn't work). I've read lots of posts around the web about the Q-LED staying yellow, but none where it just shuts off and nothing happens.

What could be wrong?

I've gone through most of the stickied suggestions, though the old system used a 2-pin speaker which I can't connect to the new motherboard. Thus I haven't been able to get any beep codes from it; I'm planning on getting a 4-pin speaker soon, though. The CPU pins aren't bent and there's no cooling paste on them or on the motherboard; and disconnecting the reset switch doesn't fix the problem. Both the 8-pins and the 24-pins AT connectors are well connected.

If I remove the RAM from the motherboard, the yellow Q-LED stays lit, so it doesn't look like it's a RAM problem (or the Q-LED would've stayed lit with RAM installed as well, I imagine). Removing the expansion cards (sound card and RAID controller) makes no difference, nor does removing the GPU or the M.2 SSD. The PSU is known good from the old system.

When I unscrewed the cooler to check for bent pins on the CPU, I saw that the thermal paste had become pretty evenly distributed onto the CPU, so I wouldn't think there's a thermal conduction issue either.