Upgraded from 2 stick to 4 sticks - Now can't POST at 3600Mhz

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Alright, maybe I goofed here

I have 2 x 16GB Sticks of GSkill TridentZ Neo RGB RAM, running at 3600MHz in my ASUS TUF B450-PLUS GAMING with an AMD 3700X

I really needed 64GB, so I bought a “matching” 2 x 16GB Kit to go to 4 x 16GB

Accidentally, I ordered the non Neo variation, everything else the same

Put the new RAM in, and it went into the safe boot mode at 2133mhz. I can only get it as high as 3200MHz, else it won’t post

  • Is the fact one kit is Neo and the other a problem?
  • Assuming that I can never get it to 3600mhz, am I going to see a performance decrease? I am also upgrading to a 5700X3D as soon as it arrives!
  • What could I do to get it to 3600MHz? I assumed it would just work
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This is normal behaviour on AMD platforms (memory controllers on AMD have always had trouble with mixed RAM). I have 2x16G and bought a second 2x16G of the same model kit, and it had trouble enabling XMP profiles. Your option is to run at the lower speed or swap out for a 2x32G kit.

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Had the exact same issue. I had 2x8GB sticks, both ran fine at XMP 3600MHz, bought the same sticks again to get 32GB total, and after that, couldn’t boot past 3200. So… I researched what safe voltage is if it comes to overclocking, and… raised the voltage by ~0.03V. After that, it works fine, and, I was even able to tighten the timings a bit.

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Try to put the same kit dimms on the same channel.

For 2DPC with dual rank/side dimms, I admit it is pretty hard to run. The best I can get with my 4x16GB DDR4 setup is 3200. It does boot at 3466, but I will not trust the stability.

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I agree with this, keep the like pairs in the same channel.

Jxd also brings up a good point about dual rank, basically you ideally want single rank DIMMs for 4x16gb or 2x32 for dual rank.

2R-2R-2R-2R can be difficult to run on any dual channel IMC, let alone AM4 chips.

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i had a 3700X and the IMC in those things in EXTREMELY picky and there’s no way it would ever post at 3600MHz with 64GB.
Once you get your 5700X3D you’re gonna most likely post without too many issues.

No, what makes the difference are the chips in those kits. If they have wildly different secondary and tertiary time there’s no training that would ever make the system post at 3600MHz. Make sure they’re equipped with EXACTLY the same chips. You can use Thaiphoon to check that.

Depends on the workload, but using dual rank kits mitigates some of the bandwidth loss.
In games you’re not gonna see any difference whatsoever because the X3D chips are less sensitive to RAM speed thanks to the bigger cache on board.

If the RAM sticks have the same exact chips on board, same bin and everything you might wanna play with the SoC voltage (never go past 1.2V) and memory voltage.
If they’re equipped with different chips find the one that’s binned the lowest and use THIS overclocking guide to set timings manually. You can also reference the same guide for voltage settings.