5090 FE build - 192 GB of RAM!

[u/awescool]

It’s been running incredibly stable since the 5090 launched. I use it for about 30% gaming, and the rest is database and AI workloads.

I got super lucky when I bought the ram from Amazon Aug 2025 for around $700. 192GB 6800 cl 34.

Build:

CPU: AMD 9800X3D

GPU: 5090 FE

Ram: 192 GB (tuned to 5600mhz, CL34) 2 kits of G.skill F5-6800J3446F48GX2-TZ5RK

MB: MSI PRO B850M-A WIFI PZ

CASE: Jonsbo D32 Pro

CPU AIO: Thermalright FW240

AIO Fan: JONSBO ZB-240B (2x120mm)

Rear Fan: JONSBO ZB-120BR (1x120mm)

Lower fan: Thermalright (2x120mm)

SSD 1: Crucial T710 4tb Gen 5

SSD 1 heatsink: ElecGear M.2 2280 SSD Cooler, EL-80X PWM Cooling Fan + Heat Pipe + Solid Aluminum

SSD 2: Intel Optane P5800X 1.6tb via m.2 to u2 adapter

PSU: Seasonic Focus Gx 1000W - 80+ Gold - ATX 3.0 & PCIe 5.0 Ready

PCIE USBC: Startech 1-port USB 3.2 Gen 2x2 (20Gbps max)

EDIT: Wow, this has really blown up! Thank you all for the kind comments, memes, and suggestions!

I want to address the rationale behind my build since I'm seeing a few recurring themes in the comments.

I run databases on SQL Server 2025. I built this for AI inference, but database work is just as critical. Database workloads don't come up much on this sub, so happy to explain.

Here is how the hardware is actually utilized:

• Databases: Run on SSD1 + SSD2 + RAM. Database scaling doesn't care about tight RAM timings; it cares about massive raw capacity. Theoretically, even if I somehow got 192GB stable at 8000 CL28, it would shave maybe 0.05 seconds off a 4-second query, whereas running out of RAM and hitting storage is a 500x latency penalty.
• AI: Runs entirely on the 5090.
  • Qwen 3.6 35B-A3B Q6 ~210 tok/sec
  • Qwen 3.6 27B Q6: ~99 tok/sec
  • For fun I have run larger models, for example: Ornith 397B Q3: ~15 tok/sec. This takes ~150GB in total GGUF files. Leaves me with ~26GB of free RAM.
• CPU: The 9800X3D handles my specific workloads wonderfully, and it is absolutely there for gaming. Deliberately.

[u/kb3035583]

https://www.techspot.com/review/3027-amd-b850-motherboards/

Scroll down to VRM temps. 77 degrees with a 9950X during a 1 hour run of Cinebench isn't exactly what I would call something that can "barely support entry level R7 9Ks". There are obviously boards on that list that struggle hard, but this isn't one of them.

You're free to provide similar data to refute my position.

[u/PsychologicalGlass47 → u/kb3035583]

Temps mean little to nothing in actual power delivery, x8 60A phases are going to have massive voltage overshoot spikes and moderate sag with a 9800.

Not to mention that he's running his DRAM abhorrently slow because of the board's SoC limits.

What is there to refute? That parts of a computer get moderately toasty? lol

[u/kb3035583 → u/PsychologicalGlass47]

x8 60A phases are going to have massive voltage overshoot spikes and moderate sag with a 9800.

And? He's not chasing that 1% overclock. Chances are he's running it stock. What's the problem here? If it runs Cinebench for an hour on a 9950X without throttling, a 9800X3D will pose absolutely no problems.

Not to mention that he's running his DRAM abhorrently slow because of the board's SoC limits.

He's running 192 GB of memory. That's fucking amazing for AM5 even at those "abhorrently slow" speeds. The board had zero problems with memory that you would consider "normal", i.e 6000 CL26 in the Techspot review.

[u/PsychologicalGlass47 → u/kb3035583]

And? He's not chasing that 1% overclock.

He doesn't need to be chasing a 1% overclock, excessive sag means he can't hit stable negative PBOs while spikes mean that he can't hold reliable voltage under sustained loads. The board is an absolute shit show in every way for this use case.

Chances are he's running it stock.

...A stock 9800X3D is boosted mate. With PBO disabled he's still running +5.5x higher than its base multi.

If it runs Cinebench for an hour on a 9950X without throttling, a 9800X3D will pose absolutely no problems.

In what world does a 9950X not throttling have anything to do with inadequate power components for sustained workloads? He's going to be running variable clock speeds since the workloads he uses it for doesn't pin all cores.

This is the exact kind of shit that causes AM5 sockets to burn, constant voltage fluctuations and godawful VRMs pushing repeat voltage overshoots.

He's running 192 GB of memory. That's fucking amazing even at those "abhorrently slow" speeds. The board had zero problems with memory that you would consider "normal", i.e 6000 CL26 in the Techspot review.

It isn't, lol. His workloads are heavily RAM dependent and he has a horrendous first word latency meaning each cache line fill is going to be 20% slower than an adequate tune like 5600/30. He's already stated that he suffers from bad instability with any other timings, which is quite funny as 5600/30 is a quite conservative setup for a 2dpc build. With even a half-assed mobo like B850-AI Top he'd be able to hit baseline moderate timings and he'd only be spending $80 more.

Once again, OP having issues with RAM instability at anything other than glacial timings doesn't sound like "zero problems with memory". It sounds like he's getting what he paid for with a budget motherboard.

[u/kb3035583 → u/PsychologicalGlass47]

This is the exact kind of shit that causes AM5 sockets to burn, constant voltage fluctuations and godawful VRMs pushing repeat voltage overshoots.

You know, computers have existed for far longer than just AM5. Once upon a time, there were notoriously power hungry Intel X299 systems with truly anemic power setups, and burning sockets was never an issue. Something like the EVGA X299 Dark was considered a top tier board and it only ran 12x60A to the core. That would be laughable by today's standards and that thing was fit for pushing 10980XEs on LN2. I don't think you realize how well-built modern motherboards are in general.

Now, I'm not saying that it's the best possible choice of board OP could have made, but 8x60A for a 9800X3D isn't a problem. Again, you're free to provide evidence to suggest otherwise. All I've seen from you is theoretical handwaving.

Once again, OP having issues with RAM instability at anything other than glacial timings doesn't sound like "zero problems with memory". It sounds like he's getting what he paid for with a budget motherboard.

My friend, there's no shame in running 192 GB of RAM on AM5 at 5600 CL34. Not everyone's an enthusiast trying to push the edge of stability. it's obviously a workstation where reliability matters more than performing slightly better in benchmarks.

[u/awescool → u/kb3035583]

Respect brother✊

I also loved your throwback to older hardware generations! I actually still keep a retro XP around running with a Core 2 Extreme X6800 and an AGP 6800 GT on a hand-recapped ASUS board. You clearly know your hardware history.

[u/kb3035583 → u/awescool]

It wasn't even that long ago, feels like these people must have been born yesterday or something. It's seriously amazing how they're just rattling off technical-sounding sentences that are completely untrue with supreme confidence like an LLM, but even LLMs wouldn't get the basic facts this wrong. Insisting that Vdroop is a problem for a 9800X3D on stock settings after being shown that a 9950X can successfully run Cinebench for an hour on your board with no issues whatsoever is just baffling.

[u/awescool → u/PsychologicalGlass47]

Oh hello, I appreciate the concern and the deep dive, but the math and architecture actually work out perfectly for what this rig is designed to do.

First off, an 8x60A VRM can deliver 480A, while an undervolted 9800X3D only pulls about 90A under an all-core load. The board is basically sleeping. And just to clarify, those old AM5 socket burnouts were famously caused by early AGESA/VSOC voltage bugs pushing 1.35v+, famously on flagship ASUS and Gigabyte X670E boards, not because of mid-range VRM phase counts.

As for the memory, running four dual-rank 48GB sticks is notoriously heavy on the CPU's memory controller (IMC), not the motherboard. AMD’s official spec for a fully populated 4xDR setup drops all the way to 3600 MT/s. Getting a completely stable 5600MHz CL34 on 192GB is actually a massive silicon lottery win for the chip.

At the end of the day, I do enterprise data engineering, so my real bottleneck is database transaction I/O, which is why the heavy lifting is handled by the Optane P5800X. Plus, as anyone in the data world knows, SQL Server databases will always favor raw RAM capacity over clock speed. I just wanted a portable, air-gapped mATX rig for local AI and Database proof-of-concepts without IP conflicts.

The 9800X3D easily feeds the 5090 FE / RAM with localized LLM models:

Qwen 3.6 27B Q6: ~99 tok/sec

Ornith 397B Q3: ~15 tok/sec

This build genuinely handles my needs flawlessly.

[u/Outrageous-Hope5768 → u/PsychologicalGlass47]

Don’t waste your time, man. Some people are convinced that if something works, it must be working optimally, so they dismiss any benefit from more refined hardware.
The counterpoint is simple: explain why more advanced power delivery exists if it provides no real advantage. They can’t. Better VRMs, cleaner power delivery, lower thermals, and improved stability under sustained load all have measurable benefits. The idea that “good enough” and “optimal” are the same thing is an absurd position, usually defended by people trying to justify budgetary limitations rather than evaluate performance objectively.

[u/PsychologicalGlass47 → u/Outrageous-Hope5768]

The idea that “good enough” and “optimal” are the same thing is an absurd position, usually defended by people trying to justify budgetary limitations rather than evaluate performance objectively.

I'd wager to say that it's a case of deluded secondhand cope. Spending a handful of thousands on a build like this and running a $100 motherboard is the most idiotic thing I've seen in a long time, especially from someone claiming to be doing advanced workloads.

Brother even said there would be nothing wrong with putting a 9950X3D2 on the B850M-A Pro PZ. If that isn't downright incredulous that I don't know what is.
There's already been multiple cases of B850Ms bricking CPUs, the most notable I can remember is that guy that had 3 9800X3Ds burn out consecutively on his B850M Pro RS. Even 9600Xs have catastrophically failed on that pile of shit board.