DDR5 4 memory sticks stability and performance

[birdie]

As late as of the summer of 2022 there were reports that ADL systems couldn't keep up with four DDR5 memory modules/sticks and as a result RAM ran at much lower speeds or the system didn't POST at all.

@W1zzard

What's your experience been like? Could you run an article about the issue or lack of?

1) Do Ryzen 7000/RPL CPUs maintain advertised DDR5 speeds with all four modules installed?
2) Are there better/worse motherboard vendors or motherboard brands in this regard?
3) What about performance? At least Ryzen 5000 CPUs showed slight performance improvements when installing four memory modules. Is this still the case for DDR5?
4) Is running four DDR5 sticks an install and forget experience or you need to tweak something, e.g. RAM/IMC voltage?

The reason I'm asking is because my current Ryzen 5800X system has 64GB of RAM (16x4, 3600MHz, CL17) and if I am to upgrade to DDR5 I want to have 128GB of relatively fast DDR5 RAM which starts at ~$400 for 6000MHz CL32 (hopefully pricing will improve soon).

 

[ir_cow]

2x Dual-Rank DDR5 barely works with Alder Lake (12th gen) at higher frequencies. It was a struggle to find a motherboard that it work with XMP auto settings @ DDR5-6000. Some I could get going with manually setting the SA, TX and VDD2. That is just two DIMMs though. I do not have another set to try out 128 GB yet. (working on it). Intel 13th Gen is MUCH better, but I haven't had time to really dive in and find a the maximum freq yet. Though G.Skill has a DDR5-7400 64GB kit coming soon. Still that isn't 4x dual-rank DIMMs. I haven't seen a motherboard QVL list with 128GB yet (4 DIMMS).

Ryzen 7000 (Zen4) hates 4 DIMMs. To get single rank to run at 6200, took a lot of trail and error with various voltages. Dual-rank DDR5-6000 (2x32GB) does work on a few motherboards I've tried, but once again that is only 2 DIMMs for a total of 64GB. As more AMD AGEAS updates roll out, I suspect DDR5-5200 for 128GB will be possible.