Which DRAM timings should I tighten at 3800Mhz?

[Machinus]

I have a pretty good B-die kit, but it's 64GB, and the IMC cannot keep it stable past 3800Mhz.

So, I'd like to tighten my timings instead to improve performance. My current configuration is:

Auros Master B550
SOC: 1.2V with "Low" LLC. I think this is 25% although the BIOS doesn't explicitly say that
DRAM: 1.4V
Timings: 16-16-16-16-36 28-52
Leaving everything else to be set by "Auto" gives these voltages and timings:

This RAM will boot at 3866, but it will fail large Prime after a few minutes, so I think there is a little more room in it.

 

[thesmokingman]

I assume those 16gb sticks so you're already ahead with being able to run them at 3800 on the FCLK. I threw specs for typical b-die at that density into dram calc. You can try targeting these timings but I'd target slightly higher than 1.4v on dram voltage. G.Skill recommended voltage for kits at this speed are 1.4v-1.45v fyi. Oh I should add as far as the settings, I don't touch PDM, GDM or manually set command rate, leave those on auto. You can go manual on those for a slight decrease in latency but you'll have to make a trade off with moar voltage.

 

[juular]

SOC: 1.2V with "Low" LLC

Isn't that a bit high ? Also, are you sure that 1.9GHz Fclk is stable on you ? Have you tested it extensively enough (like a few days or so of normal usage mixed with occasional stress tests).

 

[Machinus]

Isn't that a bit high ? Also, are you sure that 1.9GHz Fclk is stable on you ? Have you tested it extensively enough (like a few days or so of normal usage mixed with occasional stress tests).

The stock SOC is 1.2 for the 5950x on B550. That comes out of the motherboard. So, perhaps this has been increased for Zen3?

I have tested 1900fclk with many hours of Prime95 tests, and it seems stable to me. 1933 fails Prime load tests.

 

[oobymach]

tras 32
trc 48
tfaw 16

Those might not work but should, the biggest boost you can give it is from trfc but idk how low you can go with 64gb, I would start with 300-400 and if it boots try lowering it until it crashes workers as soon as you start P95 and add 50 to that value and you should have stability.

Here's what someone else was running stable with 16gb at 1.45v on a ryzen 5000

 

[PaulieG]

I've found there is significant diminishing returns when running your infinity clock past 1900. In fact, even though I have a Rev. B set that is rock stable at 4000/2000, all of my benchmarks score better at 3800/1900. So honestly, you have good timings at 3800. I'd just leave it at that if you are talking about daily use. Timings...maybe get your TRFC down a bit.

 

[TheLostSwede]

I have a pretty good B-die kit, but it's 64GB, and the IMC cannot keep it stable past 3800Mhz.

So, I'd like to tighten my timings instead to improve performance. My current configuration is:

Auros Master B550
SOC: 1.2V with "Low" LLC. I think this is 25% although the BIOS doesn't explicitly say that
DRAM: 1.4V
Timings: 16-16-16-16-36 28-52
Leaving everything else to be set by "Auto" gives these voltages and timings:

View attachment 195550

This RAM will boot at 3866, but it will fail large Prime after a few minutes, so I think there is a little more room in it.

If those are B-dies, then your tRFC is way high and should be the first thing to address.

 

[Zach_01]

I assume those 16gb sticks so you're already ahead with being able to run them at 3800 on the FCLK. I threw specs for typical b-die at that density into dram calc. You can try targeting these timings but I'd target slightly higher than 1.4v on dram voltage. G.Skill recommended voltage for kits at this speed are 1.4v-1.45v fyi. Oh I should add as far as the settings, I don't touch PDM, GDM or manually set command rate, leave those on auto. You can go manual on those for a slight decrease in latency but you'll have to make a trade off with moar voltage.

View attachment 195559

I would go with this set of timings as Calculator suggests.
Keep DRAM voltage 1.4V or maybe increase it to 1.45V if it’s not stable. b-dies dont care about voltage as long as you can keep it cool, around 40C ideally.

SoC voltage on the other hand seems a bit high. It’s not about increased voltage for the 5000 series. Some boards are feeding unnecessary high voltage to SoC. I would try around 1.10~1.12V.

tFAW and tRFC are way to high for your sticks.

In order to run above 1900MHz you must first determine if CPU subsystems can do that (UMC and IF). That is UCLK and FCLK.
You must loose timings a lot and test it. If it’s ok then you start tighten timings.

According to some experienced users the following power saving settings should be disabled when MCLK/UCLK/FCLK are OCed.

PowerDownMode: Disabled
DF C-States: Disabled
SoC/Uncore OC Mode: Enabled

 

[juular]

I have tested 1900fclk with many hours of Prime95 tests, and it seems stable to me. 1933 fails Prime load tests.

In my experience, stress tests don't catch up IF instability, you need to use the PC a few days normally, it may pass all and any stress tests for hours and then randomly crash when you browse internet or play a game.

 

[PaulieG]

In my experience, stress tests don't catch up IF instability, you need to use the PC a few days normally, it may pass all and any stress tests for hours and then randomly crash when you browse internet or play a game.

A little trick I've found that tends to catch IF instability quickly is to run a loop of Realbench benchmark with endless youtube videos playing at the same time. If a system is going to crash because of IF, it WILL happen within a couple of hours of doing this.

 

[Machinus]

I would go with this set of timings as Calculator suggests.
Keep DRAM voltage 1.4V or maybe increase it to 1.45V if it’s not stable. b-dies dont care about voltage as long as you can keep it cool, around 40C ideally.

SoC voltage on the other hand seems a bit high. It’s not about increased voltage for the 5000 series. Some boards are feeding unnecessary high voltage to SoC. I would try around 1.10~1.12V.

tFAW and tRFC are way to high for your sticks.

In order to run above 1900MHz you must first determine if CPU subsystems can do that (UMC and IF). That is UCLK and FCLK.
You must loose timings a lot and test it. If it’s ok then you start tighten timings.

According to some experienced users the following power saving settings should be disabled when MCLK/UCLK/FCLK are OCed.

PowerDownMode: Disabled
DF C-States: Disabled
SoC/Uncore OC Mode: Enabled

Thank you for the detailed suggestions. I tried to utilize all of these settings.

I have tested the new configuration a lot. Here are the current timings that appear to be stable. I'd still like to improve if I can.

 

[tabascosauz]

Thank you for the detailed suggestions. I tried to utilize all of these settings.

I have tested the new configuration a lot. Here are the current timings that appear to be stable. I'd still like to improve if I can.

What exactly are you after?

1. If it's a reasonably fast daily that's not too hard on VDIMM, the Infinity Fabric, and the UMC, then you've already got it. Those settings look just fine. Ideally, that tRFC should be 140ns-150ns, but below 4000MT/s it can be hard to stabilize tRFC at 140ns without a pretty well-binned kit given how a kit's lower limit for tRFC doesn't change yet tRFC is always in relation to memory speed. So as long as you can bring tRFC down somewhere below 160ns you're just peachy.

If your goal with this PC remains to game and not to delve into the world of B-die overclocking, then stay right where you are, verify it in HCI (to at the very least 1000%) or TM5 (3 or more runs on anta777), and go about your day.

2. If your ego is wanting more because you've seen some Tom, Dick and Harry on the internet run 3800CL14, then I'm sorry, B-die can always "improve". And there's always a lot of room to "improve" if you're chasing numbers. Question is, how much time and effort are you willing to put in to personally learn how the timings behave and do the HCI / Karhu / TM5 testing day in and day out?

Let's not forget that you're running 4 x 16GB dual rank sticks. If you want to get the most out of your kit, you're going to need to go straight to 1.5V VDIMM. But if you do, you will need to put a small fan in there dedicated to blasting air at your sticks if you're running anything more power hungry than a RTX 3060 Ti and still want your mems to remain stable. So if you're ready to go there, we can easily try for CL14 and tighter secondaries, just be aware that it may not be feasible below 1.55V.

 

[Taraquin]

I have a pretty good B-die kit, but it's 64GB, and the IMC cannot keep it stable past 3800Mhz.

So, I'd like to tighten my timings instead to improve performance. My current configuration is:

Auros Master B550
SOC: 1.2V with "Low" LLC. I think this is 25% although the BIOS doesn't explicitly say that
DRAM: 1.4V
Timings: 16-16-16-16-36 28-52
Leaving everything else to be set by "Auto" gives these voltages and timings:

View attachment 195550

This RAM will boot at 3866, but it will fail large Prime after a few minutes, so I think there is a little more room in it.

You already got some good tips, a few I can share is lower tRP, 15 or 14 is probably okay, tCL+tRCD=tRAS so 32 and tRAS+tRP=tRC so 46 or 47, tRC*6=tRFC. Try tWR 12 and tRTP 6. I would lower soc voltage a bit, 1.2 is not necissary, even at 4000/2000 I don't need over 1.12V on my 5600X.

 

[Machinus]

What exactly are you after?

I know I can get more performance out of this kit if I work on it. What I really wanted was to get my fclk higher, but the IMC does not seem to be able to support this capacity at a higher frequency, so instead I'd like to lower my timings. I'm very happy to increase DRAM voltage to 1.5 or 1.55, and I intend to put more time into this machine.

I'm already going to look more at the tRFC setting. Thank you for the information about the 140-150ns latency goal.

 

[tabascosauz]

I know I can get more performance out of this kit if I work on it. What I really wanted was to get my fclk higher, but the IMC does not seem to be able to support this capacity at a higher frequency, so instead I'd like to lower my timings. I'm very happy to increase DRAM voltage to 1.5 or 1.55, and I intend to put more time into this machine.

I'm already going to look more at the tRFC setting. Thank you for the information about the 140-150ns latency goal.

The issue with running 1.5V or 1.55V is not with the B-die itself. It'll take it like a champ. The problem is when you try to game, all of your GPU dumps all its heat directly onto your RAM. B-die is a temp sensitive IC and freaks the fk out when it gets over 50-55C. You're running an extremely high density configuration, and 1.5V is a lot of volts for 4x16GB with no spacing in between the sticks.

The tRFC recommendations were more for a set and forget daily. If that's not what you're after, go to 140ns and first make it stable, and see about getting into the 130s. tRFC is the only timing that scales as much if not more with VDIMM as tCL does, and affects your performance just as much.

Okay. First things first, almost all Gigabyte boards feature a software-visible (in HWinfo) DRAM voltage sensor that is overvolted 0.03-0.06V over what you set in BIOS. Generally people take it as being more accurate, but it's up to you which one to believe - pretty important as 1.55V is definitely up there in terms of VDIMM and you don't want to be setting "1.55V" when you're really getting 1.6V+.

Do you want to try for CL14? If so, leave your subtimings as they currently are and try for 14-16-16 to start. tCL of 14, tRCDRD of 16, tRP of 16. Make tRCDWR 14 to start. tRAS and tRC probably don't need to be ideal right off the bat, leave at something like 32 and 50 to start to make sure they aren't getting in the way. See how much VDIMM you need to boot that and be reasonably stable in something like AIDA or Geekbench 3, guessing vaguely somewhere between 1.45-1.6V.

 

[Machinus]

The tRFC recommendations were more for a set and forget daily. If that's not what you're after, go to 140ns and first make it stable, and see about getting into the 130s. tRFC is the only timing that scales as much if not more with VDIMM as tCL does, and affects your performance just as much.

Do you want to try for CL14? If so, leave your subtimings as they currently are and try for 14-16-16 to start. tCL of 14, tRCDRD of 16, tRP of 16. Make tRCDWR 14 to start. tRAS and tRC probably don't need to be ideal right off the bat, leave at something like 32 and 50 to start to make sure they aren't getting in the way. See how much VDIMM you need to boot that and be reasonably stable in something like AIDA or Geekbench 3, guessing vaguely somewhere between 1.45-1.6V.

I decided to adjust the tRFC first before moving onto trying to lower CAS. I noticed that my system seems to benefit from GDM, which may make it difficult for me to get CAS 15 stable.

I was able to get a first attempt at a lower tRFC in a few different configurations with hours of stability tests. I will come back to this after I work on CAS. Here is one configuration after 1hr of Prime Large, where I was able to get tRFC 276:

 

[Zach_01]

Its true about Gigabyte boards feeding a little more voltage to DRAM from what the setting is. Auto or manual. Having my XMP profile ON with auto Vdimm would not feed it with 1.35V but 1.36+V. I now have it on 1.44V and DRAM voltage fluctuates between 1.44~1.452V. Actually you can see it in BIOS if you re-enter it after setting it.



HWiNFO reports the same



@Machinus you should cool your dimms further. As @tabascosauz said 4 populated dimms cant circulate air around them too well. Active cooling upon them would be nice.
Also HWiNFO can report your dimm temps as well and its a more modern tool from the obsolete HWMonitor.

 

[PaulieG]

What exactly are you after?

1. If it's a reasonably fast daily that's not too hard on VDIMM, the Infinity Fabric, and the UMC, then you've already got it. Those settings look just fine. Ideally, that tRFC should be 140ns-150ns, but below 4000MT/s it can be hard to stabilize tRFC at 140ns without a pretty well-binned kit given how a kit's lower limit for tRFC doesn't change yet tRFC is always in relation to memory speed. So as long as you can bring tRFC down somewhere below 160ns you're just peachy.

If your goal with this PC remains to game and not to delve into the world of B-die overclocking, then stay right where you are, verify it in HCI (to at the very least 1000%) or TM5 (3 or more runs on anta777), and go about your day.

2. If your ego is wanting more because you've seen some Tom, Dick and Harry on the internet run 3800CL14, then I'm sorry, B-die can always "improve". And there's always a lot of room to "improve" if you're chasing numbers. Question is, how much time and effort are you willing to put in to personally learn how the timings behave and do the HCI / Karhu / TM5 testing day in and day out?

Let's not forget that you're running 4 x 16GB dual rank sticks. If you want to get the most out of your kit, you're going to need to go straight to 1.5V VDIMM. But if you do, you will need to put a small fan in there dedicated to blasting air at your sticks if you're running anything more power hungry than a RTX 3060 Ti and still want your mems to remain stable. So if you're ready to go there, we can easily try for CL14 and tighter secondaries, just be aware that it may not be feasible below 1.55V.

I know I can get more performance out of this kit if I work on it. What I really wanted was to get my fclk higher, but the IMC does not seem to be able to support this capacity at a higher frequency, so instead I'd like to lower my timings. I'm very happy to increase DRAM voltage to 1.5 or 1.55, and I intend to put more time into this machine.

I'm already going to look more at the tRFC setting. Thank you for the information about the 140-150ns latency goal.

I understand wanting to see what the memory is capable of, as my hobby is overclocking and benchmarking. I literally don't game on PC or do anything so cpu or memory hungry to justify the hours and hours I spend tweaking cpu/gpu/memory. It just makes me happy to see what I can squeeze out of hardware. If this is you too, I totally get it. However, if you are looking for significant gains for real world application from adjusting secondary timings, you will be sorely disappointed. Once you get a decent overclock and tighten primary timings there is nothing really noticeable beyond that. Just be aware of why you are doing it and if it's time spent wisely or not.

 

[tabascosauz]

I decided to adjust the tRFC first before moving onto trying to lower CAS. I noticed that my system seems to benefit from GDM, which may make it difficult for me to get CAS 15 stable.

I was able to get a first attempt at a lower tRFC in a few different configurations with hours of stability tests. I will come back to this after I work on CAS. Here is one configuration after 1hr of Prime Large, where I was able to get tRFC 276:

So you already can see what I mean when I say that you're going to be thermally limited. It wasn't even gaming and your sticks are already exceeding 55C. You're also going to have to provide some feedback on that VDRAM sensor like I said, at this point I have no idea what your 1.45V VDIMM is actually turning into. HWInfo will provide it under the motherboard sensors group.

Also, stop using HWMonitor and install HWInfo. For testing just use HCI Memtest to start. P95 Large is good as a UMC stressor, but it's not a first line memtest.

145ns tRFC is fine from a performance perspective. If you want to chase numbers then you can go lower, but looking at your temps I'm afraid you already have no wiggle room.

If you want to run CL15 as a compromise, you will be running 2T command rate as I just don't see a way you'll have the VDIMM headroom to push 1T without GDM. So you'll just have to benchmark it (AIDA64, membench in DRAM calc, Geekbench 3, etc) to see if it's worth it over CL16.

Also, get thar tRP back to 16. No point lowering it below tCL, you're not in balls-to-the-wall territory to warrant that yet. You're just costing yourself VDIMM.

 

[thesmokingman]

He's still using hwmonitor.... geeze at this? And your temps are getting out of hand.

 

[Machinus]

So you already can see what I mean when I say that you're going to be thermally limited. It wasn't even gaming and your sticks are already exceeding 55C. You're also going to have to provide some feedback on that VDRAM sensor like I said, at this point I have no idea what your 1.45V VDIMM is actually turning into. HWInfo will provide it under the motherboard sensors group.

The temperatures slowly climb to mid 50s because the airflow is good, but not directly over the DIMMs. I have to get some new hardware to add to give adequate cooling to my RAM. That will be an interesting project.

In the meantime, I am doing shorter stability tests.

Right now, I am stable for about an hour with these settings:
DRAM 1.488V (from HWiNFO)
3800Mhz
15-15-15-15-30
tRC 45
tRFC 270
Most of the other settings are "Auto," including 2T command rate.

So, I was able to get CAS 15 at 3800, although it does produce a lot of heat. Since it's a very gradual temperature increase, I think adding active cooling will really help.

He's still using hwmonitor.... geeze at this? And your temps are getting out of hand.

I have changed to HWiNFO. I apologize.

 

[TheLostSwede]

The temperatures slowly climb to mid 50s because the airflow is good, but not directly over the DIMMs. I have to get some new hardware to add to give adequate cooling to my RAM. That will be an interesting project.

In the meantime, I am doing shorter stability tests.

Right now, I am stable for about an hour with these settings:
DRAM 1.488V (from HWiNFO)
3800Mhz
15-15-15-15-30
tRC 45
tRFC 270
Most of the other settings are "Auto," including 2T command rate.

So, I was able to get CAS 15 at 3800, although it does produce a lot of heat. Since it's a very gradual temperature increase, I think adding active cooling will really help.


I have changed to HWiNFO. I apologize.

So by going to 2T command rate, you just wasted everything you gained by going from CAS16 to CAS15.

 

[thesmokingman]

So by going to 2T command rate, you just wasted everything you gained by going from CAS16 to CAS15.

Nah, he wrote its on auto. Auto = 1T. A lot of settings are fine on auto contrary to what a lot of posters think.

 

[TheLostSwede]

Nah, he wrote its on auto. Auto = 1T. A lot of settings are fine on auto contrary to what a lot of posters think.

Not on Ryzen systems, it's 2T or gear down.

 

[thesmokingman]

Not on Ryzen systems, it's 2T or gear down.

I don't think that's correct. I don't bother touching gdm, pdm, 1t and yet I'm running 1T.