[SOLVED] OC'ing Ram with a boost clock CPU?

[Jagscorpion]

So I'm familiar with the basics of overclocking RAM and trying to get a 1-1 ratio on AMD with the fclk. What I'm trying to figure out is how that interacts with the boost clock? If the CPU is constantly changing its speed how am I supposed to keep the RAM synced? Is there something I'm missing? I'm trying to decide between 3600 mhz and 3200 for a Ryzen 9 5900x which has a base clock of 3700. So my thought is to very slightly OC the ram to hit 3700, wich should still be in the range of what the infinity fabric should support, but then if the CPU is constantly boosting won't that completely mess things up and force the ram into asynchronous mode?

 

[MeanMachine41]

Hi Jagscorpion 👍

Official support for the 5900x is up to 3200Mhz.
You can choose 3600Mhz OC RAM however there will not be a D.O.C.P profile for easy Overclocking and you will have to manually enter Timings and Voltage (SPD) information in Bios.
It is the strength of the chips IMC that will determine if you can achieve the Rams rated speed with no guarantee.
Yes it is desirable to get a 1-1 ratio fclk - mclk and AMD recommends users use DDR4-3600 with the FCLK set to 1800 MHz for optimal performance.
If using boost is unstable then choose to have an all core manual overclock as I have done.

 

[CountMike]

So I'm familiar with the basics of overclocking RAM and trying to get a 1-1 ratio on AMD with the fclk. What I'm trying to figure out is how that interacts with the boost clock? If the CPU is constantly changing its speed how am I supposed to keep the RAM synced? Is there something I'm missing? I'm trying to decide between 3600 mhz and 3200 for a Ryzen 9 5900x which has a base clock of 3700. So my thought is to very slightly OC the ram to hit 3700, wich should still be in the range of what the infinity fabric should support, but then if the CPU is constantly boosting won't that completely mess things up and force the ram into asynchronous mode?

No relation OCing CPU and RAM. One will not affect OC of other one.
You don't have to have CPU and RAM frequencies synced. RAM controller on those Ryzen are on separate chip in the CPU which takes care of syncing.
Depending on your MB and it's BIOS, FCLK will be automatically adjusted to memory XMP and be able to be manually adjusted to RAM frequency up to point of max RAM frequency allowed by MB and BIOS.
Zen3 is capable of 4000MHz+ memory frequency, the rest is up to MB.
PS.
OCing ram by 100MHz is not going to bring any practical gains, may even be worse if you have to raise Cl or other latency.

 

[CountMike]

Hi Jagscorpion 👍

Official support for the 5900x is up to 3200Mhz.
You can choose 3600Mhz OC RAM however there will not be a D.O.C.P profile for easy Overclocking and you will have to manually enter Timings and Voltage (SPD) information in Bios.
It is the strength of the chips IMC that will determine if you can achieve the Rams rated speed with no guarantee.
Yes it is desirable to get a 1-1 ratio fclk - mclk and AMD recommends users use DDR4-3600 with the FCLK set to 1800 MHz for optimal performance.
If using boost is unstable then choose to have an all core manual overclock as I have done.

That depends on the MB and it's BIOS, My MB for instance has DOCP going up to 4000MHZ with FCLK up to 2000 although my installed RAM is 3600MHz by it's XMP.

 

[MeanMachine41]

That depends on the MB and it's BIOS, My MB for instance has DOCP going up to 4000MHZ with FCLK up to 2000 although my installed RAM is 3600MHz by it's XMP.

Now that's interesting. I've never come across an XMP profile for 3600Mhz that would work with a Ryzen chip.
If indeed you managed to get 3600Mhz then enlighten us on how you achieved it?
Technically it's possible but you must be a genius lol

 

[CountMike]

Now that's interesting. I've never come across an XMP profile for 3600Mhz that would work with a Ryzen chip.
If indeed you managed to get 3600Mhz then enlighten us on how you achieved it?
Technically it's possible but you must be a genius lol

Genius ? Maybe but there was nothing genius about this one. Stuck RAM in proper holes (A2 and B2), turned on DOCP 3600, frequency 3600 (second XMP on RAM) and it worked. Checked FCLK and it was 1800 so everything run fine although at Cl 18. (XMP said it should be 17).
Second part may be a bit bizarre. More or less by accident, I set DOCP at 3000 and frequency to 3600MHZ and now it works at 3600MHz but with Cl 16. Looking at Dram calculator i realized that couple of settings were out of whack and now it breaks 51000 point barrier in Aida test.
3800MHz was different story though, had to do it all manual with help from Dram calculator but Cl shot up to 26 so it was slower despite higher frequency. 4000MHz at ridiculous Cl 37 was practically unusable. posting but not entering Windows or Linux, too much of OC stretch for this memory although it's b-die.
I was thinking about getting proper 4000MHz RAM but too expensive for diminishing gain returns.
500 series chipset MBs and zen3 can do much better and easier.

 

[mamasan2000]

Genius ? Maybe but there was nothing genius about this one. Stuck RAM in proper holes (A2 and B2), turned on DOCP 3600, frequency 3600 (second XMP on RAM) and it worked. Checked FCLK and it was 1800 so everything run fine although at Cl 18. (XMP said it should be 17).
Second part may be a bit bizarre. More or less by accident, I set DOCP at 3000 and frequency to 3600MHZ and now it works at 3600MHz but with Cl 16. Looking at Dram calculator i realized that couple of settings were out of whack and now it breaks 51000 point barrier in Aida test.
3800MHz was different story though, had to do it all manual with help from Dram calculator but Cl shot up to 26 so it was slower despite higher frequency. 4000MHz at ridiculous Cl 37 was practically unusable. posting but not entering Windows or Linux, too much of OC stretch for this memory although it's b-die.
I was thinking about getting proper 4000MHz RAM but too expensive for diminishing gain returns.
500 series chipset MBs and zen3 can do much better and easier.

Source: https://github.com/integralfx/MemTestHelper/blob/master/DDR4 OC Guide.md#amd---am4
"Geardown mode (GDM) is automatically enabled above DDR4-2666, which forces even tCL, even tCWL, even tRTP, even tWR and CR 1T. If you want to run odd tCL, disable GDM. If you're unstable try running CR 2T, but that may negate the performance gain from dropping tCL, and may even be less stable than GDM enabled.

For example, if you try to run DDR4-3000 CL15 with GDM enabled, CL will be rounded up to 16.
In terms of performance: GDM disabled CR 1T > GDM enabled CR 1T > GDM disabled CR 2T."


I wonder if it is B-die. Shouldn't require such a bump up in CL, no matter what RAM it is. Does it boot at 3600 Mhz with tRFC at 360? That equates to 200 nanoseconds and to my knowledge, only B-die can do that low a tRFC.
https://github.com/integralfx/MemTestHelper/blob/master/DDR4 OC Guide.md#trying-higher-frequencies Scroll down a little.

1800 Mhz Fclock all 5000-series should be able to reach, 1900 Mhz not so many and very very few reach 2000 Mhz. Some have found that setting Fclock to 2000, SOC voltage is raised like crazy. So that has to be dialed down. And it 'might' work.

 

[Unolocogringo]

Now that's interesting. I've never come across an XMP profile for 3600Mhz that would work with a Ryzen chip.
If indeed you managed to get 3600Mhz then enlighten us on how you achieved it?
Technically it's possible but you must be a genius lol

I have a similar system.
Asus Prime X570
R5 3600
16 GIG Corsair (Samsung die) 3600 XMP running just fine.
Was able to drop from 20-23-23-43-66 1T to 18-19-19-43-67 1T no problems.

Just looked to check my numbers and my XMP profile is for 3596 not 3600 and reports as 1799.
Close enough.

 

[CountMike]

I have a similar system.
Asus Prime X570
R5 3600
16 GIG Corsair (Samsung die) 3600 XMP running just fine.
Was able to drop from 20-23-23-43-66 1T to 18-19-19-43-67 1T no problems.

Just looked to check my numbers and my XMP profile is for 3596 not 3600 and reports as 1799.
Close enough.

That much variance is due to BCLK not at 100MHz all the time, negligible at worst.

 

[alexbirdie]

but then if the CPU is constantly boosting won't that completely mess things up and force the ram into asynchronous mode?

No.

CPU-clock and RAM-clock are independent from each other.