ASUS Prime Z490-A does not post with BIOS defaults & 2 ram sticks

Randy_H

New build (9/26/20); ASUS Prime Z490-a, i9-10900K, G. Skill Ripjaws V 64GB (2X32GB) DDR4-3600, Noctua NH-U14S , Seasonic Focus Plus 750 watt Gold.  System does not reliably post with both RAM sticks at BIOS defaults. System does post with just one RAM stick at defaults. After multiple restarts, system eventually posts in "Safe Mode" which allows resetting BIOS to XMP I and then it will post/boot into WIN 10. Also, BIOS crashes every time on clicking "QFan" option in BIOS. I emailed ASUS and after troubleshooting they suggest RMA motherboard.
 However, once I set BIOS to XMP I, system seems stable.  I want to lock all cores at turbo speed but ASUS overclock  procedures call for starting with BIOS defaults. So, do I RMA an otherwise okay board, or is this be a RAM issue, or what? 30 day return period is almost up on the RAM but I bought a 2 yr plan on the MB. Would rather not switch it out unless absolutely necessary. Any suggestions?

JS_MC

Are you able to clear the CMOS?

From what you've described this seems to be a motherboard issue. Resetting the CMOS(BIOS) might clear things up. This will clear any settings that you've changed on the motherboard.

Try resetting using the jumper on the board. Make sure you power off and unplug the PC before clearing the BIOS. You can also try removing the CMOS battery and leave it out for 10 or so minutes. Sometimes the use of the clear CMOS jumper doesn't always clear things up 100%.

Randy_H

Thanks Landshark. Cleared CMOS as part of ASUS troubleshooting, even removed removed battery (but not for 10 minutes). Guess I’ll try that as I’m out of options at this point. 

JS_MC

You're welcome. I'll chat with a couple of other friends to see if we can't think up any other solutions for this issue. Let us know if that works!

Randy_H

Thx - did some more troubleshooting: Cleared CMOS/battery>10 minutes. Posts fine with EITHER Ram stick in recommended single channel DIMM_A2 slot. (QFAN in Bios works also.) This leads me to believe that both RAM sticks are good. Next, I loaded both sticks - one in DIMM_A2, one in DIMM_B2 as recommended in user guide.  Does NOT post. Blue/black pixelated screen, no logo, no nothing.  Maybe DIMM_B2 slot is bad? Next I removed the stick in DIMM_A2 leaving one stick in DIMM_B2.... and system posts fine. So why won't it post with both sticks? 
Next I moved both sticks  to DIMM_A1 and DIMM_B1 (not the recommended config.) - no go. System power cycles repeatedly without posting. Argh. Next I put one stick back in A2 and system posts again. So we're back to square one. Must be an issue with dual channel mode or incompatibility with these G. Skill sticks. 
Seems like I need to return wither the MB or the RAM or both and start over?

JS_MC

I think you've narrowed it down correctly. It seems like this could be a compatibility issue with the motherboard and the RAM since it appears that both are working independently, yet not together. I'd recommend either trying altogether different RAM or replacing the motherboard.

Our service department could also offer diagnostics, though there will be a diagnostic fee.

Randy_H

Latest: Recalling that I was previously able to boot into BIOS & Windows with both RAM sticks under XMP, I confirmed the following procedure :  Load one stick (in A2) and boot at defaults. Enable XMP I in BIOS, restart, then shutdown after successful post. Install 2nd ram stick (in B2), and restart. BIOS now posts successfully with both sticks, with XMP I enabled. So, I have a working system, but it's potentially unstable as it will not post with BIOS defaults. I will run some stress tests and possibly attempt the ASUS AI overclocking to see what happens. Still thinking I should probably return the MB?

JS_MC

I think it may be an issue with the base timings on the RAM. It may require XMP settings for it to function properly. Without running further stability tests, I wouldn't be sure of where the fault would lie. Though, based on your troubleshooting and the recommendation from ASUS, I don't think it would be illadvised to return the MB.