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  #1  
Old 08-10-2017, 09:03 AM
Gothmoth Gothmoth is offline
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Default Vengeance LED 3000 MHz with Ryzen - 4DIMM question

hello,

i have a ryzen 1700 build that i did run with 2x8GB Corsair Vengeance 3000 MHz.

CMU16GX4M2C3000C15

they did run fine with 2966 MHz.

today i added another pair of sticks so that i have 32GB of ram.

i know that ryzen has some limitation when you run memory in all 4 slots.
i think 2666 MHz as stated by AMD ?


but i read that people are able to run all 4 dimms with 2966 MHz.
i should be able to OC the ram even when 4 DIMM are used... or not?

how do i do that? when i set the ram to DOCP 2966 MHz i get into a bootloop.

i have an asus strix b350 F mainboard.

Last edited by Gothmoth; 08-10-2017 at 09:05 AM.
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  #2  
Old 08-10-2017, 06:21 PM
c-attack c-attack is offline
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You have combined two different kits together. There is a reason you are supposed to buy a matched set. Sometimes it is possible to get them to work together, but the higher the speed the more difficult it can be. On Ryzen it might be even more difficult as they try and sort the early memory issues.
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  #3  
Old 08-10-2017, 06:58 PM
Gothmoth Gothmoth is offline
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first a clarification, i speak about modules from the same brand, same make and model, same electronics on the PCB.
when moduls are sold under the same name and type but use different chips (some hynix, other samsung) it´s something different.
but that should not happen with brand names like corsair.


Quote:
Originally Posted by c-attack View Post
You have combined two different kits together. There is a reason you are supposed to buy a matched set. Sometimes it is possible to get them to work together, but the higher the speed the more difficult it can be. On Ryzen it might be even more difficult as they try and sort the early memory issues.
yes i read that again and again for years but i doubt that corsair (or any other manufacturer) is doing more than testing the speed of individual modules.

i just doubt that they put a memory module, that does not work well with 3 other modules, in a different kit of the same speed.

lets think about it.

corsair first tests if a module meets the tolerances to be branded as a 3000MHz module.

then they test a kit of four 3000MHz ram modules and one does not play well with the other 3.
corsair then puts it into a different 3000MHz kit and tries it with 1 or 3 other modules again?
and if that does not work they try it again with another set of 3000MHz modules?

if a ram module is sorted out of such a kit, it sure will not make it into another kit that runs at 3000MHz. i just doubt that.
it will maybe branded as a 2666MHz module then.

honestly, i call these "tested kits" clever PR with not much real world value.
you can be sure that the modules run at the stated speed... sure.. but i doubt that they are "matched together" other than by each module fulfilling the tolerances.
and a module either passes the tolerances or not (passes individually, without influence from other modules in the kit).

and if that is the case, it doesn´t matter if you buy one 4x8GB kit or two 2x8GB kits.

one thing that seems to support this is, that 4x8GB kits have the same problem.

if i am wrong i would like to see a whitepaper or any real info, beside the PR talk, that describes in detail how corsair is matching those kits.

but what does corsair expect then.. that people sell their 2x8gb kits because they decided to upgrade to 4x8GB a few month later?


ryzens official support for 4 dimms is 2666MHz as a maximum.
that seems to be the problem i need to overcome.
question is.. lower timings, more voltage?

ps: just to make that clear.... both 2x8 kits are CMU16GX4M2C3000C15

psps: sorry if that reads confusing.. i am not native english speaking. :)

Last edited by Gothmoth; 08-10-2017 at 08:01 PM.
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  #4  
Old 08-11-2017, 08:58 AM
c-attack c-attack is offline
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You can call PR or sales tactic if you like, yet people continually show up here combining two boxes of the same exact kit and it doesn't work at higher speeds. 2133, 2400 probably. Then it falls apart as the frequency goes up. I don't have any illusions about tiny little elves testing every single kit by hand. Even the PR literature states this is only on the highest end modules. However, whether or not the two boxes come from the same batch of original material might matter. You can't always rely on version number for that. Either way, you set yourself up for someone to close the door in your face. For every motherboard problem you have have, the manufacturer will blame the memory. Each of the memory vendors are also likely to give you the "don't mix kits" and be done with you. Several of them expressly list it as an term in the warranty. So if you combine kits, you are on your own from a service perspective.

Unfortunately, I am not sure you can easily differentiate between that potential issue and the current Ryzen limitations, however I would approach it from the Ryzen angle first. Some people are able to clock up to 3000 and I would follow their approach. I am not a Ryzen owner, so I can't guide you there. A bump to 1.37 or 1.38v would be my first step, but I would not go much beyond that before altering timings. It could also be things like VCCSA and IO voltages are key with the Ryzen platform and sometimes this is the solution in mixing kits. Very fiddly and time consuming.
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  #5  
Old 08-12-2017, 10:21 AM
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HisEvilness HisEvilness is offline
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Ryzen is a Dual Channel so getting 3000mhz will only work on 2 slots if you use 4 slots it will cut down the speed probably at 2133.
If you want 32GB you need 2 sticks of 16GB not 4 sticks of 8GB, And using kits you need to match them you could buy 2 x 2 kits but you need to buy them at the same time so they are most likely from the same batch.
Any time in between will make it likely they are not from the same batch thus will not work or poorly.
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  #6  
Old 08-12-2017, 02:55 PM
Gothmoth Gothmoth is offline
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Quote:
Originally Posted by HisEvilness View Post
Ryzen is a Dual Channel so getting 3000mhz will only work on 2 slots if you use 4 slots it will cut down the speed probably at 2133.
If you want 32GB you need 2 sticks of 16GB not 4 sticks of 8GB, And using kits you need to match them you could buy 2 x 2 kits

after a bit of fiddling i run the 4x 3000 MHz dimms at 2800MHz.

Quote:
...but you need to buy them at the same time so they are most likely from the same batch.
Any time in between will make it likely they are not from the same batch thus will not work or poorly.

yeah as we talked about above.... i have yet to see hard proof for that.
people repeat that like gospel but my own experience is different.
if they use different chips it might be the case, i aknowledged that above.

but can you show me tests where they show that 2 kits of 2 dimms won´t work but one kit of 4 dimms work?

i don´t mean hearsay... i mean a real test? ;)

i just borrowed a 4 dimm kit from a friend and it´s exactly the same.
it won´t run faster than 2800 MHz and his kit is even a 3200 MHz kit.

Last edited by Gothmoth; 08-12-2017 at 02:58 PM.
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  #7  
Old 08-13-2017, 02:34 PM
fanskap fanskap is offline
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Sometimes theres nothing wrong with your memory even though it might be easier with a matched kit to reach higher speeds. Does your boards bios have the agesa 1.0.0.6 update from amd? That helped a lot with memory compatibility.

I have crosshair vi hero and an 1800x and have managed to get my 4x8gb vengeance rgb 3466 to run at 3333. Only 2x8 can run at 3466 stable.

Once when i tried running 2 different kits of vengeance led 3200 2x16gb i couldnt get them stable at 3200 only 2933. That might have been because they are dual rank more than one beeing hynix and the other samsung-b chips though so cant tell for certain.
Ryzen seems to have an easier time with samsung-b than hynix.

Some things you can try if your bios has the option is different procodt settings. Try a higher voltage on the memory if you havent already and you can also try setting command rating to 2T if your boards default is 1T.
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Old 08-28-2017, 12:44 AM
Lodion Lodion is offline
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Quote:
Originally Posted by Gothmoth View Post
after a bit of fiddling i run the 4x 3000 MHz dimms at 2800MHz.
Hi, what part number are you running with 4 DIMMs at that speed? CMU16GX4M2C3000C15? I'm going to be using a pair of CMU16GX4M2C3200C16R, wondering if I should splash out on a second kit.
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