Advice on 2 x (2 x 16GB) kits of 5600MHz RAM

[CJS23]

Hi

I made what could be described the "newbie" error of buying 2 of thse kits https://www.corsair.com/uk/en/p/memory/cmh32gx5m2b5600z36k/vengeance-rgb-32gb-2x16gb-ddr5-dram-5600mt-s-c36-amd-expo-memory-kit-cmh32gx5m2b5600z36k?srsltid=AfmBOopltGzNZb6cC5pFAQee4NDmuYJb0qTv15AbykHGH7xAgYyd1gE_

I'm clearly (hindsight being 20/20 vison) unable to run at EXPO II at those speeds with the 2 x identical kits

My options are to either return and exchange for QVL listed kits or go down the rabbit hole of exploring a plethora of timings and voltages shenanigans.

Is anyone up for the challenge, lol?

What are the suggested timings to head towards 5600?

[c-attack]

Mixing kits is usually problematic on DDR5, but it's also worrisome if they won't play together at 5600.  Usually it's easier at lower frequencies.  If they only work together at 4800 or lower, you certainly want to exchange and if you need 64GB you should be looking at 2x32 kit anyway.  None of the DDR5 boards work better with 4 modules and you always pay a price for using 4 even when they come from a matched kit.  

You can't use EXPO, XMP, AXMP or any of the other various presets when combining kits.  The preset values were written for 2 modules and there are timings that change when you use 4.  The place to start is turning off EXPO and then input the 4 primary timings (36-36-36-76) into the BIOS along with the 1.25v DIMM voltage.  The VDIMM voltage is likely in a separate place, but this is very BIOS version dependent.  Your motherboard should set values for all remaining timings based on its programming.  They are generally comfortable values aimed at making sure the PC boots up.

Your motherboard model also matters here.  If you are using a budget targeted board, it makes things more difficult.  

[CJS23]

Thanks so much for the response and advice. I would imagine the ASUS TUF GAMING X670E-PLUS WIFI is a decent board for overclocking and I'll have a play when I get home tonight from work and post my results.

It's been a while since I've geeked out so I'm looking foward to the journey 🙂 (Picture is when I had just the 1 kit in)

Edited November 12 by CJS23

[CJS23]

@c-attack - really struggling to find the appropriate "VDIMM" voltages settings in my UEFI/BIOS - for this mainboard - https://dlcdnets.asus.com/pub/ASUS/mb/13MANUAL/PRIME_PROART_TUF_GAMING_AMD_AM5_Series_BIOS_EM_WEB_EN.pdf?model=TUF GAMING X670E-PLUS WIFI  - copuld you please advise where I set the 1.25v? I'm lost in multiple options! 😊

[c-attack]

On Asus boards it will be in the "Advanced BIOS" (F7 to toggle between EZ and Advanced).  Then go to the second column from the left.  The name changes based on motherboard, but it's typically something like AI Tweaker, Extreme Tweaker, etc.  This is the main column with all the main settings and also where you find the manual DRAM timings.  Go all the way to the very bottom of that column.  Asus puts the VDIMM and other advanced memory voltages at the very end.  You only need to set the main VDIMM voltage.  You can leave all the others on auto.  

[CJS23]

6 hours ago, c-attack said:

On Asus boards it will be in the "Advanced BIOS" (F7 to toggle between EZ and Advanced).  Then go to the second column from the left.  The name changes based on motherboard, but it's typically something like AI Tweaker, Extreme Tweaker, etc.  This is the main column with all the main settings and also where you find the manual DRAM timings.  Go all the way to the very bottom of that column.  Asus puts the VDIMM and other advanced memory voltages at the very end.  You only need to set the main VDIMM voltage.  You can leave all the others on auto.  

Aha! That's brilliant advice. I'd changed 2 or 3 voltage settings to 1.250v and I had to pop out the CMOS battery to get it to post after that - I'll test tonight and report back

[CJS23]

@c-attack - assuming I've changed the correct setting (there wasn't one named "VDIMM" verbatim) - no POST and forced to rmove CMOS battery and short the cage with power lead removed to bring it back to life  

[c-attack]

@CJS23 Timings are right.  However, that is the IO memory controller voltage.  On your Asus board it is likely the primary module voltage is usually abbreviated as "VDD". Leave VDDQ alone.  The BIOS will automatically adjust it based on the value you input for VDD.  Put VDDIO/MC back on auto by entering "a" into that field.  

 

Edited November 13 by c-attack

[CJS23]

@c-attack - after following your method. It finally POSTed at 4400MHz. The only deviation from your method was to set both "Power Down Enable" and "Memory Context Restore" from "Auto" to "On". Thoughts?

[CJS23]

By changing tRC to 112, I have achieved 4600MHz but it's not stable. I'm out of ideas, tbh 

[c-attack]

Eesh..... if you have to drop the frequency to 4400-4800 to get it to boot with the mixed kits, then I think you need to go in a different direction.  That's a massive penalty and we haven't even checked if this stable.  -1600 MTs just to boot and that's at CAS 36.  I would look at your return options and weigh the cost of a 2x32 at 6000 if you need the full 64GB.