Flummoxed: XMP seems to make system unstable

lewisr · November 23, 2020

Would appreciate any/all input. Here's the situation:

I've been getting random reboots but ONLY when at idle -- literally when I've walked away from my machine or turned my back for a sec. Never while actively in use
No BSOD, minimal info in Event Viewer -- just a Critical 41/Kernel-Power, but all the Bugcheck Codes and Params are 0
Occasionally rather than rebooting into Windows, the system takes me to a BIOS screen letting me know that the current config won't boot. Restoring BIOS to defaults permits me to boot into Windows (and the only deviation from default is the turning on of XMP)
These happen very intermittently and I think they coincided with me having enabled XMP in BIOS; hard to know as the system itself is very new
The usual benchmarks / tests have revealed no errors / instability
Disabling XMP seems to have stabilized things, but again, since it's so intermittent it's hard to know if it's truly "better" or not
I am not even a novice at tweaking, but having researched this issue thoroughly, I turned the XMP profile on but attempted to manually dial the speed down to 3000 (i.e., from the 3200 that the XMP profile sets) to see if that would be stable. It... didn't go well (system failed to boot)

System particulars:

Aorus Z490 Pro AX / latest BIOS
i9-10850K at stock
G.Skill TridentZ RGB 32GB DDR4 3200MHz (running at 2133 with XMP disabled)
Windows Home 20H2 build 19042.630
Idle temps @ ~28 with XMP off; ~32/33 with it turned on

Other things I've tried:

Reinstalling Windows multiple times
Swapping M.2 (boot drive)
Updated every driver, everywhere (e.g., all the Intel stuff, all of the MoBo-specific drivers, video, etc.)
I have NOT tried swapping out the RAM; I would need to remove the AIO radiator and fans in order to do so, and I'm not able to commit to that right now

Net/net:

To be honest, I'm not seeing a perceptible difference in running day-to-day at 2133 versus 3200. But I paid for 3200, you know? So I'd love for it to work

Many thanks in advance for any thoughts here!

Mateyyy · November 23, 2020

What exact memory kit is it that you're using?

What's your VCCSA (or System Agent) voltage set to when XMP is enabled (you can check using HWiNFO64)?

lewisr · November 23, 2020

20 minutes ago, Mateyyy said:

What exact memory kit is it that you're using?

What's your VCCSA (or System Agent) voltage set to when XMP is enabled (you can check using HWiNFO64)?

Thanks so much for the quick response.

Exact memory kit: F4-3200C16-32GTZR
VCCSA: "average" is 1.320 with XMP on; 1.063 with it off

Thanks again.

Mateyyy · November 23, 2020

6 minutes ago, lewisr said:

Thanks so much for the quick response.

Exact memory kit: F4-3200C16-32GTZR

VCCSA: "average" is 1.320 with XMP on; 1.063 with it off

Thanks again.

If it's a two stick kit (so 2x16GB, as opposed to 4x8GB), install them in slots 2 and 4 on the board if you haven't already.

Go into the BIOS and make sure that enabling the XMP also sets your DRAM voltage to 1.35V.

If those two things were already true, enable XMP and set the memory's frequency to 2933MHz, then test the memory for stability with HCI MemTest (or even MemTest86 should give you a fairly rough idea of whether your memory's stable or not).

If the memory is stable at 2933MHz, you could either just have a super weak memory controller on your CPU. If it's still not stable, then there's probably something up with the memory itself, or with the board (either physically, or the BIOS revision you're running is borked).

lewisr · November 23, 2020

11 minutes ago, Mateyyy said:

If it's a two stick kit (so 2x16GB, as opposed to 4x8GB), install them in slots 2 and 4 on the board if you haven't already.

Go into the BIOS and make sure that enabling the XMP also sets your DRAM voltage to 1.35V.

If those two things were already true, enable XMP and set the memory's frequency to 2933MHz, then test the memory for stability with HCI MemTest (or even MemTest86 should give you a fairly rough idea of whether your memory's stable or not).

If the memory is stable at 2933MHz, you could either just have a super weak memory controller on your CPU. If it's still not stable, then there's probably something up with the memory itself, or with the board (either physically, or the BIOS revision you're running is borked).

Thanks again. Confirming that it's 2 sticks, inserted into slots 2 and 4. Also confirming that XMP sets the voltage to 1.35V.

To be explicit, your suggestion is to set what is referred to as "Memory Frequency (MHz)" in my BIOS to 2933, correct? This is what I had previously set to 3000 (with XMP enabled) and which refused to boot. I have NOT tried 2933 yet -- just want to be sure that I am looking at the correct parameter.

Many thanks

Mateyyy · November 23, 2020

11 minutes ago, lewisr said:

To be explicit, your suggestion is to set what is referred to as "Memory Frequency (MHz)" in my BIOS to 2933, correct? This is what I had previously set to 3000 (with XMP enabled) and which refused to boot. I have NOT tried 2933 yet -- just want to be sure that I am looking at the correct parameter.

Yup, XMP but with 2933MHz, as opposed to 3200.

Technically, the memory controller on your CPU is only rated for 2933MHz. Granted, the chances of the IMC to not handle anything more than 2933MHz are... quite slim, but at least if the same is happening at 2933MHz, then that kind of rules out the weak IMC possibility.

In that case (if it's still unstable at XMP with 2933MHz), disable XMP and run MemTest with the memory running stock.