Can't run DDR4 at rated speed

[PageFault]

Hi, I am reaching out for an advice on memory overclocking. I am running G.Skill F4-4000C19D-32GTZR which is CL19 4000Mhz on ASUS ROG Gaming Z490-E + i9 10900K. I am experiencing situation I do not understand.

When I set XMP or XMP2 4000Mhz machine has stability issues. However, if I keep fiddling with settings, eventually it loads and runs at 4000Mhz and is stable for days and days until I shutdown the PC. When I turn on PC after the shutdown, it is unstable again, and only after fiddling/restarts it runs stable again. Which makes me think that something is not initialized identically during the boot in BIOS, it's like there's some difference between restarts that I am not aware of.

Any suggestions? CPU is overclocked too, so perhaps my system simply cannot be stable at rated memory speeds. But what really confuses me that sometimes it runs rock solid at 4000Mhz, which makes me feel I am very close to reaching it (currently running 3600/16-15-15-36). Thanks in advance.

 

[EarthDog]

I'd update your BIOS if you haven't already...

Try adding 0.1-0.2V of System Agent/VccSA and see if that helps. You've got 32GB and that's a bit more difficult to stabilize than the 2x8GB more common at the time.

To ensure it's not the CPU, take that back to stock and work on the RAM. Once we get the RAM stable, then re-enable the stable CPU settings.

 

[PageFault]

Actually I just updated the bios, before update I was able to only achieve 3100Mhz. After update, it seemed like I can now do 4000Mhz except the weirdness described above. That said even stable 3600Mhz is a big progress for my PC. Thanks for your advices, will give it a go.

 

[Mr.Scott]

I have same ram in one of my machines. SA voltage 1.2v, DRAM voltage to 1.75v. Running 4000 @ 16-16-16-39 1T

 

[PageFault]

1.75v is a bit high huh, is that safe? Gonna try SA/VCCSA voltage bump in a bit...

What's your VCCSA Scott(y )?

 

[Mr.Scott]

1.75v is fine. VCCSA 1.2v

 

[EarthDog]

1.75V when the kit requiers 1.35V??

The sticks aren't running past their speeds, or lower timings. I can see increasing 0.1V for giggles, but 0.4V, that seems like a ton for no reason. Why would that help?

 

[Mr.Scott]

1.75V when the kit requiers 1.35V??

The sticks aren't running past their speeds, or lower timings. I can see increasing 0.1V for giggles, but 0.4V, that seems like a ton for no reason. Why would that help?

Because that's what it took to get to a benchable cl16. Stock timings are cl19. Sticks are not particularly good. Disappointing actually.

 

[EarthDog]

He's trying to get it stable at stock (xmp) speeds and timings, not CL16. Is the advice still the same?

 

[PageFault]

I do not appreciate threads without closure, so I'll just share the outcome. I gave up on reaching 4000Mhz and right now focused on getting stable 3600Mhz. No matter what I do I can't get stable 4000Mhz after shutdown(s) (I tried things listed above). I stand by my words that I see stable results after mutliple reboots etc, but after shutdown things go bad. I have a theory why - I use ASUS Extreme Auto settings for CPU, and I am happy with 5.2Ghz 24/7. But my guess is Auto does not result in same settings on every boot. That said, stable 5.2Ghz is good for me and I do not want to spend time re-overclocking my CPU, so right now decided to focus on finding stable timings at 3600Mhz, and I suspect I might have to go even lower. Considering that CPU is rated for 2933Mhz RAM, even 3100Mhz is overclock - erson-shrugging:. Agree with Scott though, disappointing.

Sincere thanks to you guys, much appreciated.

 

[Mr.Scott]

He's trying to get it stable at stock (xmp) speeds and timings, not CL16. Is the advice still the same?

But what really confuses me that sometimes it runs rock solid at 4000Mhz, which makes me feel I am very close to reaching it (currently running 3600/16-15-15-36). Thanks in advance.

This messed me up. My bad for misunderstanding.

 

[EarthDog]

I use ASUS Extreme Auto settings for CPU, and I am happy with 5.2Ghz 24/7. But my guess is Auto does not result in same settings on every boot.

That may be true (can't confirm) but that feature is only with CPU clock speeds AFAIK(?)... so it doesn't affect memory. It's also why earlier I said to DISABLE it (run teh CPU at stock) and try the memory... did you do that?

 

[PageFault]

That may be true (can't confirm) but that feature is only with CPU clock speeds AFAIK(?)... so it doesn't affect memory. It's also why earlier I said to DISABLE it (run teh CPU at stock) and try the memory... did you do that?

Please do not get me wrong, I read your suggestions and I am not ignoring them, but I have my priorities, and my priority is CPU overclock, so I do not want to spend time re-overclocking my CPU. If that means going lower on RAM speed so be it. Sure, I want highest RAM speed but not at a cost of CPU overclock.
I just noticed something interesting. All guides suggest VCCIO/SA no higher than 1.2v. But I noticed that Auto, depending on RAM speed, goes into very high values, up 1.44v. So my last attempt will be setting fixed voltages and trying RAM overclock that way.

 

[EarthDog]

First... I hear what you're saying.

so I do not want to spend time re-overclocking my CPU

You flipped a switch... no?

 

[PageFault]

You flipped a switch... no?

No, I am keeping CPU overclock, but I will try setting SA/VCCIO manually instead of Auto and see what happens, this is the last thing I'll try. And no, I did not try restoring CPU settings to default as I have many non-CPU settings configured that I do not want to restore.

 

[EarthDog]

Roger.

There are ways if you so choose to pursue. We're here for you.

 

[PageFault]

Roger.

There are ways if you so choose to pursue. We're here for you.

You guys were helpful. Thanks a lot, I learned some new things. I'll let you know if it was VCCIO/SA. One weird thing I see again and again is what I described in my initial post - I would find some settings that seem to work rock solid, but things go bad after the shutdown. This makes no sense as this is semiconductor hardware, not tubes... but I can't stop thinking that it might have to do with temps somewhere, when things reach some temperature overclock is stable, but not below those temps. Very weird.

 

[EarthDog]

That's odd it goes bad after shutdown... the settings should be the same, so... that's odd. I mean for giggles you can replace the CMOS battery, but, I highly doubt that's it.

Temperatures can absolutely play a role in stability. But it's typically towards the limits that things get can unstable.

 

[PageFault]

That's odd it goes bad after shutdown... the settings should be the same, so... that's odd. I mean for giggles you can replace the CMOS battery, but, I highly doubt that's it.

Temperatures can absolutely play a role in stability. But it's typically towards the limits that things get can unstable.

And, typically hot is the problem, not cold, right?

 

[EarthDog]

And, typically hot is the problem, not cold, right?

Right... unless you're talking sub-ambient cooling methods.