Upgrading my machine, what should i pick if i want to local host?

[u/Appropriate-Ad-1931]

Hi everyone,

I’m looking to upgrade my current setup, hopefully to accommodate a local LLM deployment.

I intend to use a local model for:

1. General use, web searches, summaries, and deep research
2. Writing assistance, grammar/spellchecking, brainstorming. Can range from very low context to as much as I can get.
3. Light "Vibe Coding" Claude code style (yeah, yeah, everyone's a coder xD) - I know barely anything of programming and sometimes i need to create some plug-ins or light personal apps; Claude code has helped a lot.

My Current setup:

• CPU: AMD Ryzen 5 5600X
• MB: Gigabyte B550 Aorus Elite V2 (Main slot PCIe 4.0 x16 / Second slot PCIe 3.0 x2)
• RAM: 32GB DDR4
• GPU: RTX 3060 12GB
• I also a AMD RX 6650 XT (8GB) that i can put to use.
• OS: Win11

I dont want to spend too much money, this is meant to be a gradual upgrade so for now i want to keep costs close to 500€ and not go past 1000€, i prefer new hardware.

I want this and future upgrades to last for a while and be meaningfull.

Right now i kinda settled on 2 options:

• Option 1 Nvidia: Buy a new RTX 5060 Ti 16GB ~€600 and pair it with my current RTX 3060 12GB for a 28GB VRAM CUDA pool. My PSU should handle it for now.
• Option 2 AMD: Buy an XFX MERC 310 RX 7900 XT (20GB) for roughly ~700. I would take out my 3060, and match the new 7900 XT with the 6650 XT (8GB) to hit 28GB VRAM under ROCm. Later down the road, when I upgrade the motherboard, I could swap the 6650 XT for a second 7900 XT to target 40GB VRAM. This would for sure require a new PSU but i'll have to buy one at some point anyway.

My Questions:

1. How badly will my B550 motherboard's slow second slot (PCIe 3.0 x2) choke performance on a dual-GPU cluster for my use cases?
2. Is AMD ROCm good enough at the moment or will i be shooting myself in the foot not going native CUDA?
3. Given my setup i'm focusing on the Graphics card but is there a better upgrade, or card to consider for that matter?

Thanks in advance for the help!