u/BitGreen1270

Hi - I am basically building a PC for running local LLM models on. The specs I have finalized are:

• AMD Ryzen 7 9700x
• Ram 64GB - KD5BGUA80-60A300G KLEVV CRAS V 6000 CL30 RGB DDR5 (2x32GB)
• SSD - kioxia exceria basic 2tb nvme m.2 gen.4
• msi 5090 ventus 3x oc 32gb
• lian li edge gold 1200w gold atx 3.1

The store recommended the Asus Prime X870-P but on the whole reviews have been meh - especially techpowerup. Also reviews on newegg. Mostly around bad bios, slow boot, weird pcie issues, frequent RMA etc.

I thought the x870 might be a better option than B850 because of USB4. But not at the cost of peace of mind.

The X870E seems like overkill. What would you recommend for this kind of build? The gaming I do is like kingdom rush, so this is purely going to be an LLM machine.

I don't mind spending a little bit more if it means I don't have to bring it back to the shop to exchange for a different one. I'm spending my kidney and a piece of my liver on this build, last thing I want is to have it create additional problems.

Thanks in advance!

EDIT: RESOLVED! I went with the Gigabyte B850 AORUS ELITE WIFI7 ATX AM5 as suggested by u/Born_Bad_1294! Saved a bit of money and the PCI5.0 is not affected by maxing out my storage capacity or using the expansion slots.

I'm considering biting the bullet and getting a pc with the following specs:

• 5090
• Amd 9950x3d
• X870 motherboard
• 32gb ram (16x2) CL32

EDIT2: Price for this is falling in the arena of 5500-6000 USD where I live.

Obviously costs a bomb. But I'm hoping it will become cost effective over time (10 years probably) as I intend to use it to learn as much as I can about LLMs and ideate and work on use cases for them. I also feel the future is going to be LLMs in some form or other and it's better late than never to try and keep up.

My questions

1. how does it perform with dense models like qwen3.6-27B and gemma4-31B. These are most likely the models I'll be trying to build applications around.
2. The alternative is using adhoc compute resources on vast.ai or maybe spend more for Google cloud or something. But that gets expensive also fast. I can keep costs down by keeping it adhoc but that increases friction.
3. My only application is LLMs. I don't play games or anything else that needs a gpu like this one.

Edit: forgot to mention, my current system is a lenovo e14 laptop with 780m igpu and 32gb ram.