DDR5 RAM won't POST on Z690/Z790 — the fix that actually works

You just built a new rig with a Z690 or Z790 board — DDR5 RAM, Intel 13th gen. You flip the PSU switch, hit power. Fans spin, RGB lights up, but your monitor stays black. The motherboard's DRAM LED is stuck on solid red or orange. You've reseated the sticks, tried one stick, swapped slots. Nothing.

What's actually happening here is memory training failed. DDR5 is more aggressive than DDR4 — the board tries to dial in timings and voltage on first boot. If it doesn't lock in within a few seconds, it hangs. The board is not broken. The RAM is not dead. The fix is about forcing the board to restart training from scratch.

Why DDR5 training fails

DDR5 modules have on-die ECC and two independent channels per stick. The initial training sequence is more complex than DDR4. Most boards default to a safe but slow training routine. If you power-cycle too fast — like pressing the reset button or flipping the PSU off — you can leave the board in a half-trained state that won't recover on its own.

The real fix is a specific sequence that clears the training data and forces a fresh start.

The fix: step by step

1. Shut down completely. Hold the power button for 4 seconds until the board is off.
2. Flip the PSU switch off. Unplug the power cable too. Wait 10 seconds.
3. Remove the CMOS battery. Use a plastic tool or fingernail to pop it out of the socket.
4. Short the CMOS clear pins. On most boards, there's a two-pin header labeled CLR_CMOS or JBAT. Use a screwdriver to bridge them for 5 seconds. I've seen people skip this step and wonder why the battery pull didn't work — the board can hold residual charge that keeps training data alive.
5. Wait 30 seconds. This gives all capacitors time to drain.
6. Reinstall the CMOS battery. Make sure it clicks in.
7. Install only one stick of RAM. Use slot A2 (second slot from the CPU). This is the primary slot for almost all Z690/Z790 boards. Don't ask why it's not A1 — the board expects A2 for single-stick boot.
8. Plug in the power cable, flip the PSU on.
9. Boot and wait. This is the hard part. The board will go through training again — you'll see the DRAM LED cycle or stay solid for up to 2 minutes. Do not touch anything. Don't press reset. Don't turn it off. Let it sit. On my Asus ROG Strix Z690-A, it took 90 seconds the first time.

If you see the display come on after 2-3 minutes, you're golden. Go into BIOS and load optimized defaults. Then shut down and add the second stick in slot B2.

If it still fails

Three things to check next:

• BIOS version. Some early Z690 boards shipped with BIOS that barely supported DDR5 at all. Update to the latest using the USB flashback feature (no CPU needed). Check your motherboard manual for which USB port and file name format it expects.
• RAM kit compatibility. Look up your exact kit on the motherboard's QVL list. I've seen Corsair Vengeance and G.Skill Trident Z5 kits that just don't train on certain board revisions. If yours isn't listed, it might still work after a BIOS update — or it might never work reliably.
• Try a different board. If you have a friend with another Z690/Z790 board, swap the RAM in. If it trains there, your board might have a bent pin in the socket or a damaged memory channel.

The DDR5 training failure is infuriating because it looks like dead hardware. But in 9 out of 10 cases, it's just the board needing a clean slate and a full minute of patience. The CMOS reset + one stick + long wait sequence has never failed me across Asus, MSI, and Gigabyte boards with both Hynix and Samsung-based kits. Try it before you RMA anything.