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Question RAM Frequency compatibility on a motherboard check

May 12, 2020
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Hi,

I'm on picking parts stage for a first setup, and I need to make sure of some details that I might misunderstood since.. a long time maybe.

:My question basically, is the motherboard supported frequency is specific? or like is it a range?
for example, this is a MSI B450 Tomahawk MAX memory supporting (first motherboard):

  • DDR4 MEMORY
1866/ 2133/ 2400/ 2667Mhz (by JEDEC)
For AMD Ryzen Gen3 (R5/R7/R9)
2667/2800/2933/3000/3066/3200/3466/3600/3733/3866/4000/4133 by A-XMP OC mode
For AMD Other CPU
2667/2800/2933/3000/3066/3200/3466 by A-XMP OC mode

And this is the supported frequency's for another motherboard MSI B450-A PRO MAX (second motherboard)
  • DDR4 MEMORY
1866/ 2133/ 2400/ 2667Mhz (by JEDEC)
For AMD Ryzen Gen3 (R5/R7/R9)
2667/ 2800/ 2933/ 3000/ 3066/ 3200/ 3466/ 3733/ 3866/ 4000/ 4133 MHz (by A-XMP OC MODE)
For AMD Other CPU
2667/ 2800/ 2933/ 3000/ 3066/ 3200/ 3466 MHz (by A-XMP OC MODE)


The RAM sticks I have is a T-Force 8GBx2 Xcalibur 3600Mhz, and my processor is AMD R5 3600
The question is: I see the frequency 3600Mhz is only on the first motherboard, but not on the second one
does it mean its not supported on the second motherboard and will not work (won't boot)?
or is it a range between 2600 and 4133 in both motherboards?

Another question: A-XMP OC is overclocking the Memory? can someone give me a short explanation of the memory overclocking? and is it gonna make the RAM age faster? can't I just plug in the 3600Mhz that I already have without OC ?

Any help is appreciated!
 

Karadjgne

Titan
Ambassador
Take motherboard support lists with a grain of salt. Motherboard has very little to do with ram speeds as such. That's reliant on the cpu. The fastest ram supported by a Ryzen currently afaik is Corsair's LPX 5000MHz.

Meaning that the cpu will also support anything lower, regardless of whether Amazon decided to list it or not on motherboard specs.

The only thing required is a bios that will recognize the ram, of which all bios recognize 3600MHz for 3 series Ryzen
 
May 12, 2020
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Take motherboard support lists with a grain of salt. Motherboard has very little to do with ram speeds as such. That's reliant on the cpu. The fastest ram supported by a Ryzen currently afaik is Corsair's LPX 5000MHz.

Meaning that the cpu will also support anything lower, regardless of whether Amazon decided to list it or not on motherboard specs.

The only thing required is a bios that will recognize the ram, of which all bios recognize 3600MHz for 3 series Ryzen
I'm sorry, but I'm a bit confused of your reply, and it kinda didn't answer some of my questions.
But I checked the motherboard compatibility and found that it does support the RAM I have:


But didn't get my answer for if it works on the second motherboard in that example.
 
I'm sorry, but I'm a bit confused of your reply, and it kinda didn't answer some of my questions.
But I checked the motherboard compatibility and found that it does support the RAM I have:


But didn't get my answer for if it works on the second motherboard in that example.
"For AMD Other CPU" means AMD APU processors like Ax-xxxx series because they are not true Ryzen but previous APU series with modifications to work with DDR4 and fit in AM4 socket, they are not capable of high memory speeds.
First series of Ryzen were not really capable of more than 2933-3000 MHz RAM but could be hoaxed to 3200MHZ memory.
Second and 3rd series Ryzen are capable of over 4000MHz depending on BIOS options.
Motherboard had some influence on memory speed, most MBs with 300 series chipset had bad memory paths to CPU so that was a major problem with high speed RAM. 400 chipset MBs are much better in that aspect.
What might be confusing is reference to JEDEC and XMP profiles. Memory without XMP profile are somewhat limited to speed because of standards but RAM with XMP profile is capable of speeds as high as XMP profile and in some cases even higher by buy overclocking.
To make story short, both MBs are capable of running memory with XMP up to 4133MHz if used with 2nd and 3rd gen Ryzen.
3600 MHz RAM with CL16 or lower are just about sweet spot performance/price wise.
 

Karadjgne

Titan
Ambassador
Ram is made of chiplets cut from silicon. Even the factory cannot predict exactly what speeds are attainable from any sheet, as each sheet has different impurities, different grades of silicon. So the OEM makes a batch of ram, then bins it to see just how high it will go according to the items settings.
Then corsair or gskill orders a certain speed and timing set, so the OEM wraps up a binned set and sells it.

The default speed for DDR4 is 2133MHz. It includes tables (JEDEC) for above default, to cover the memory controller speeds of cpus, Intel kabylake is 2400, Ryzen 3 is 2666 etc. Xmp is Intel extreme memory profile, it's the factory set OC beyond default, but naturally some companies find using Intel standards on amd motherboards/bios to be a conflict of interest, so have their own versions like DOCP or EOCP or A-xmp etc. But it's basically the same result if a different process.

3600 ram is not 3600. 3600 ram is 2133 that can be enabled by you and your bios to attain a stable speed of 3600. But being an OC it's on you to agree to that and enable it yourself since some cpus do not run at 3600 speeds stable. You could use 3600 on kabylake, but there's no guarantee the pc will get past post. So a default is set liw enough to enable every pc to post.

That's why there's no plug n play ram, not everyone can use it whether the motherboard is capable or not, it's on the cpu to determine.
 
May 12, 2020
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"For AMD Other CPU" means AMD APU processors like Ax-xxxx series because they are not true Ryzen but previous APU series with modifications to work with DDR4 and fit in AM4 socket, they are not capable of high memory speeds.
First series of Ryzen were not really capable of more than 2933-3000 MHz RAM but could be hoaxed to 3200MHZ memory.
Second and 3rd series Ryzen are capable of over 4000MHz depending on BIOS options.
Motherboard had some influence on memory speed, most MBs with 300 series chipset had bad memory paths to CPU so that was a major problem with high speed RAM. 400 chipset MBs are much better in that aspect.
What might be confusing is reference to JEDEC and XMP profiles. Memory without XMP profile are somewhat limited to speed because of standards but RAM with XMP profile is capable of speeds as high as XMP profile and in some cases even higher by buy overclocking.
To make story short, both MBs are capable of running memory with XMP up to 4133MHz if used with 2nd and 3rd gen Ryzen.
3600 MHz RAM with CL16 or lower are just about sweet spot performance/price wise.
I fully understand all what you said now,

In my case, the motherboard I'm choosing is the first one "MSI B450 Tomahawk MAX" I'm assuming its the 400 chipset MB, correct?.
Without XMP my RAM will be originally 2400Mhz (SPD Speed).

So back to comparing those MBs, if we add that 3600Mhz RAM on the second MB which doesn't support the 3600 XMP Profile, it will be lowered to 3466 in XMP? Its not on its supports list right?

Also about RAM CL, my 3600 is CL18, and lower CL is better right?, but I did some research and here's what I found:
I couldn't find 3600Mhz C16, its not a thing or something? there is only C18 for that.
Also 4000 is C18, so lower CL is better not right? and CL is related to Timings right?

Note: when you reply to these questions I wrote here please mind using a white space between each answer, I'm get confused when you type a newspaper it makes me forget what I even asked, I really apologize for that :LOL: and really appreciate the help! ❤
 
May 12, 2020
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Ram is made of chiplets cut from silicon. Even the factory cannot predict exactly what speeds are attainable from any sheet, as each sheet has different impurities, different grades of silicon. So the OEM makes a batch of ram, then bins it to see just how high it will go according to the items settings.
Then corsair or gskill orders a certain speed and timing set, so the OEM wraps up a binned set and sells it.

The default speed for DDR4 is 2133MHz. It includes tables (JEDEC) for above default, to cover the memory controller speeds of cpus, Intel kabylake is 2400, Ryzen 3 is 2666 etc. Xmp is Intel extreme memory profile, it's the factory set OC beyond default, but naturally some companies find using Intel standards on amd motherboards/bios to be a conflict of interest, so have their own versions like DOCP or EOCP or A-xmp etc. But it's basically the same result if a different process.

3600 ram is not 3600. 3600 ram is 2133 that can be enabled by you and your bios to attain a stable speed of 3600. But being an OC it's on you to agree to that and enable it yourself since some cpus do not run at 3600 speeds stable. You could use 3600 on kabylake, but there's no guarantee the pc will get past post. So a default is set liw enough to enable every pc to post.

That's why there's no plug n play ram, not everyone can use it whether the motherboard is capable or not, it's on the cpu to determine.
Yes that is true,

I checked the compatibility on my MB "B450 Tomahawk MAX" in CPU and I saw the Core Name on each CPU which like a family tree,.
I also see that the memory is related to those Core Name's,

and that is for my MB which is AMD, and I found my RAM in the RX-3X00 (ex: R5 3600)

So like that, what If I didn't find my RAM in that Matisse Core Tree? and its a 3600Mhz, will it won't work? that list can't list every RAM that's ever made.

Thanks for all the information by the way!
 

Karadjgne

Titan
Ambassador
You can use 3600 on a 2nd release cpu just fine. Sort of. There's 2 things that can happen, one of which will happen.
  1. The bios can refuse the ram, simply not accept it in combination with that cpu, for all intents and purposes the ram won't work as intended and may only work if downstepped to 3200/3466.
  2. The ram works as intended, but the cpu doesn't. 2nd release cpus had a limitation on the Infinity Fabric of 3466MHz. After that, they automatically switched from a 1:1 ratio to a 2:1 ratio, and really slowed down the fabric clocks. Basically you'd get better performance at 2400 than 3600 on a 2nd release Ryzen. This put 3200MHz as the sweet spot since 3466 is unpredictable, if the motherboard bumps it to 3467MHz, you'd get stutters as the fabric switches back and forth between 1:1 and 2:1.
If you are stuck on using 3600, it's pretty much going to require manual settings to lower than 3466MHz, or xmp profile if the ram has it as an option.
 
May 12, 2020
31
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You can use 3600 on a 2nd release cpu just fine. Sort of. There's 2 things that can happen, one of which will happen.
  1. The bios can refuse the ram, simply not accept it in combination with that cpu, for all intents and purposes the ram won't work as intended and may only work if downstepped to 3200/3466.
  2. The ram works as intended, but the cpu doesn't. 2nd release cpus had a limitation on the Infinity Fabric of 3466MHz. After that, they automatically switched from a 1:1 ratio to a 2:1 ratio, and really slowed down the fabric clocks. Basically you'd get better performance at 2400 than 3600 on a 2nd release Ryzen. This put 3200MHz as the sweet spot since 3466 is unpredictable, if the motherboard bumps it to 3467MHz, you'd get stutters as the fabric switches back and forth between 1:1 and 2:1.
If you are stuck on using 3600, it's pretty much going to require manual settings to lower than 3466MHz, or xmp profile if the ram has it as an option.
Just to be clear, 2nd release cpu's you mean the (e.g.: RX-2X00) ?
because I'm not having this 2nd gen cpu and never will,
I'm having the 3rd gen CPU R5 3600

Unless If I'm mistaken on that.. I hope you correct me right.
The specifications I have:
MB: MSI B450 Tomahawk MAX
CPU: R5 3600
Memory: T-Force 8GBx2 3600Mhz CL18
 
Just to be clear, 2nd release cpu's you mean the (e.g.: RX-2X00) ?
because I'm not having this 2nd gen cpu and never will,
I'm having the 3rd gen CPU R5 3600

Unless If I'm mistaken on that.. I hope you correct me right.
The specifications I have:
MB: MSI B450 Tomahawk MAX
CPU: R5 3600
Memory: T-Force 8GBx2 3600Mhz CL18
Yes, Second gen Ryzen that start with 2000 but without G at end (Zen+), and 3rd gen Ryzen (Zen2) which is your R5.3600, can handle RAM above 4000MHz, the rest is up to MB and it's BIOS which is also capable of same speeds with last BIOS version.
400 series chipsets are b450 and x470 and have improved memory slot topology and are more capable than 300 series (A320, b350 and x370).
To be clear,300 series chipset itself is not at fault but 400 and 500 series are better made motherboards. Chipset itself is not involved in memory handling, memory controller (IMC) is in the CPU.
 

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