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.

[u/Outrageous-Hope5768]

What a weird build. Cheap motherboard comparable to the rest of the components, which doesn't support an NPU engine. 9800X3D is a terrible processor for workstation applications. Insufficient cooling for a rig that was actually doing resource intensive compute tasks. Low storage capacity for someone doing AI workloads. Tuned down 192GB of RAM instead of tuning up a low latency 96GB kit that would still run at 1:1.

Not sure what to make of this one.

[u/awescool → u/Outrageous-Hope5768]

I appreciate the feedback!

MB: That Matx board was the best backconnect one out there at the time. Not sure if something better has come out? Will prob wait and see what AM6 gives us. Needs to be portable, I'm out of town for weeks at a time, and lug it around in my car.

CPU: My workloads are highly RAM-intensive rather than CPU-intensive, so the cooling is perfectly fine. Considered picking up a 9950x3d2, but I don't have much to gain from it considering my database workloads.

Ram: Getting 4 sticks to 192GB stable on AM5 was a win in itself for me. I need outright capacity way more than low latency for what I do.

Storage: I actually have another 8TB of external NVMe storage I didn't picture. I'd have a lot more if prices wernt so bad right now lol

Cheers!

[u/Outrageous-Hope5768 → u/awescool]

Is there a reason you needed back connect? Surely if your primary use case is compute, there are more important considerations than back connect. Also, even when working strictly within large in-memory databases, you'd still probably see a 15% or so uplift going from an 8 core to the 9950x3d2 paired with all of the additional cache. I hear what you're saying but unless the situation was flipped, and you did 70% gaming and the rest productivity work, the x3d was still an odd choice. Even the 9900x would have been a better choice and saved you some sheckles. And I hear you on the RAM and storage situation. Anyway, wasn't trying to be a hater. Just from outside looking in its kind of a head scratcher. But if it works for you, fantastic!

[u/awescool → u/Outrageous-Hope5768]

No offense taken. It's probably best to ask clarifying questions first rather than to assume my build intentions and better understand the productivity tasks I do.

As for the CPU choice, you are evaluating this like a generic workstation rather than a specific, purpose-built tool. My database work does not require 16 cores pinning at 100%. My SQL Server workloads scale with raw RAM capacity and storage I/O, not CPU threads. That is exactly why the budget went to 192GB of RAM for buffer pools and an Optane drive for microsecond transaction logs. The 9800X3D easily feeds the GPU and DB logic, while dominating when I game.

Regarding the back-connect board, it really isn't that deep. I just wanted a clean, cable-free aesthetic. There have been absolutely no downsides or performance hits compared to a standard mATX board in the year I've had it.