192gb DDR5 9950x AMD5

Hardware Hub
,
1

Hello folks,

I just wanted to hear from folks who have been able to get 192gb DDR5 working on 9950x (or 7950x). I thought 9950x improved memory compatibility?

I am looking to replace my ESXi box which is currently running 5950x with 128GB RAM.

I don’t necessarily need fastest RAM. But I need something that is rock stable even at 5200Mhz or something. If VM creation fails on ESXi because of memory errors, it gets pretty funky to debug it.

Also which motherboard has best support for 192gb DDR5? I am primarily looking into MicroATX form factor because of space I have. But I am open to options.

2

Only 3600MT/s is guaranteed. 5200MT/s may not work.

3

Yeah, getting 4x sticks of dual rank RAM all running together on enthusiast grade boards will likely limit bandwidth/latency or be unstable.

You can check the latest AMD 9950X specs which are similar as those shown in the video https://www.amd.com/en/products/processors/desktops/ryzen/9000-series/amd-ryzen-9-9950x.html

Basically only 2x DIMM configuration is faster, still DDR5-3600 limit for 4x dimms.

My AMD 9950X build has 2x 48 GB G.Skill Trident Z RGB 96 GB (2 x 48 GB) DDR5-6400 CL32 and running “gear 1” uclock=mclk=3200Mhz for DDR5-6400 at EXPO/XMP voltages with inifinity fabric slightly OC’d to 2133MHz…

I wish I could get 4x dimms at this speed hah… Haven’t tried, not gonna…

4

Ha. I was getting hopeful seeing some reddit posts. I wonder how much of speed difference is between 3600 vs 5200 speed for something like virtualization, compiling and running database etc.

I know games benefit for fast RAMs, but I am yet to see a benchmark that quantifies speed difference for other kind of workloads.

2 Likes
5

Yeah good question. Just saw a recent Ryzen 9950X DDR5 benchmark results over at phoronix which shows how the higher end stuff impacts different workloads. Maybe could extrapolate downwards from there?

If I had 192GB @ DDR5-6400, I’d probably try to do AI LLM inferencing with some of the big Mixture of Experts (MoE) models like DeepSeek etc… Memory bandwidth really bottle-necks CPU inferencing, especially with the “deep” models e.g. 70B and 123Bs e.g. ~2 tok/sec. The MoE models have less active parameters so are a little more forgiving e.g. ~7 tok/sec.

If you plan to have that many VMs actively carving up the RAM, or have a database big enough to need that much cache it might be worth having more slower RAM rather than either not run it or be forced to SWAP more than one would like.

It’s a big price jump, but there are some Threadrippers and Xeons that can probably get you 4x or more channels of DDR5-5200… Probably not in MicroATX either hah…

Keep us posted with your max stable speed if you do roll the dice! :game_die: haha… Cheers!

6

Theres also the option of epyc. Getting cheap nowadays. Not ddr5 but a great platform for lots of memory and memory channels.

1 Like
7

Yeah, I could boot 4x48 DDR5-5200 Micron B die with a 7950X but it wasn’t stable even with default timings. 4800’s fine.

I’m not aware of any meaningful differences. FWIW, personally I like ASRock so I used them for my 192 build.

Indeed. Even ASRock Rack just redirects to the WRX WS90 Evo. They do deep mATX SP6, though.

1 Like
8

Looks like this post got featured in latest video from level1tech and @wendell had some luck in getting 4x48GB working at 5200Mhz on x870! That sounds amazing.

I also noticed RAM from Nemix - https://www.newegg.com/nemix-ram-192gb/p/2SJ-000N-00R14?Item=9SIA7S6K8B0523 being sold on newegg that directly claims compatibility with motherboards.

I wonder if Nemix’s claim will hold up.

2 Likes
9

Hah yes I came here again after watching the ASRock Taichi X870E and X870E Lite video featuring this forum thread xD

Interesting that Nemix RAM kit is advertising compatibility at higher speeds. The advertised specs only show timings of CL 46 @ 1.10 volts.

I haven’t done enough testing to see how overall RAM bandwidth (e.g. 80000 MB/s AIDA64 benchmark) vs latency (e.g. 70ns) effect various workloads. I gotta spend some time tuning and playing hah…

Also curious if I could achieve DDR5-5200 on 4x48GB DIMMs on my R9950X and “old” ASRock Taichi X670E haha… Is it the CPU or the MoBo or a combination of both that improves the chance of running stable? (probably both, but makes me want to gamble haha…)

10

Both, yes, as well as probably how much headroom the DRAM has (A/M-die versus B-die). It’s pretty clear AGESA’s also involved, presumably by influencing how memory training’s conducted, and my experience is DIMM thermals also become significant around DDR5-4800.

1 Like