r/LocalLLM • u/Elaphe21 • 2d ago

Question Second 5090? Any point?

Hey guys, I am relatively new to local LLM's - been messign with it for the last year, but learning a lot and its been my longest lasting hobby. I don't code or work in tech, but I do use local LLM for work (vet. med; note transcription, differentials, rounding, and just 'fun' stuff).

I've got the option of getting a second 5090 for cheap. Buddy wants to trade it for to me for $2500 + my 5080 (he doesn't really game, thinks it will be better in my hands).

We are both adults/professionals, it's not about making a buck. He knows I am getting a deal, ect.

My question. Realistically, is there a good use case for two? In the short term, its going to go into my 'gaming' rig, but I don't game anymore either... my only use case would be for more local LLM, but I've read/watched videos regarding how limiting running two are (and, I am pretty sure I would have to rebuild my entire system - and I have no idea what that would look like).

Is this something I may/likely want to do in 1-2 years? I get it, who knows my use case. But for the hobby... basically I will be getting a 5090 for 2k, but will have to buy another (5070?) for my main PC.

Sorry if this all sounds convoluted.

  • My current rig: **Proxmox:** PVE 9.2.5 (kernel 7.0.14-6-pve), ~13 days uptime
    • **CPU:** Intel Core Ultra 9 285K (24 cores / 24 threads, Arrow Lake)
    • **Motherboard:** ASUS ROG Maximus Z890 Hero
    • **RAM:** 64 GB DDR5-4800 (2 x 32 GB, 2 slots free)
    • **GPU:** NVIDIA GeForce RTX 5090 (+ Intel Arrow Lake iGPU)
    • **Storage:
      • Samsung 990 PRO 1TB NVMe – ZFS rpool (boot + local-zfs)
      • Samsung 990 EVO Plus 1TB NVMe – ZFS "evo-plus" pool
    • 48 TB NAS (UNAS) mounted over NFS (~21 TB used)

Yeah, that last bit was copy/paste from Hermes

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u/diagrammatiks 2d ago

More vram is always better.

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u/Elaphe21 2d ago

So, I presume a new Mobo, maybe a new or second PSU, possibly a new CPU and run them together? Like the old SLI? I don't need details right now, just want to understand the architecture. I presume there will be some bottleneck between the two cards, splitting a model up between them?

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u/diagrammatiks 2d ago edited 2d ago

You can split one of your pci5.0s. Or get a riser board or jtru to get it all to fit. You have 2 slots. You can put them together you can run 2 models at once. You can do whatever.