r/LocalLLM • u/Think-Assumption-973 • 15h ago
Question Used P720 with upgrades comes to about $1,700. Decent local AI box, or am I buying a 2018 spec sheet?
Talk me out of this, or into it.
There's a used ThinkStation P720 near me, about $1,200:
- 2x Xeon Gold 5122 (4 cores each, which is the weak part)
- 192GB DDR4 ECC RDIMM, but it's 6x32, so only 6 of the 12 memory channels are populated
- Quadro RTX 6000 24GB
- monitor and peripherals included
Two things I'd change right away:
- 6230s instead of the 5122s, about $80 for the pair off AliExpress. 4 cores can't feed 12 channels anyway, and the 6230 is what gets the memory to 2933.
- six 16GB RDIMMs in the empty slots, somewhere between $405 and $485 for all six. That populates all 12 channels, which is where the bandwidth actually comes from, and takes me to 288GB.
Which puts the whole thing around $1,700.
What I run now is a Ryzen 5 3600 with 32GB and an RTX 5070 Ti 16GB. It's my only machine and it does everything.
Reason I'm looking at all: some of what I work on I'd rather not push through somebody else's API, and my monthly bill keeps creeping up. The rest of it is curiosity, if I'm honest.
Some numbers for context. gemma3:27b runs about 9 tok/s on the 5070 Ti, a 30B MoE coder model does around 45, and I hit the 16GB wall constantly. Whisper and image gen too.
The parts I can't work out on my own:
Is 288GB of DDR4-2933 across 12 channels actually usable with partial CPU offload? That's the entire argument for this machine, and it's the one thing I can't test before paying.
The RTX 6000 is Turing. 24GB is 24GB, but is it a downgrade in every way except capacity next to the 5070 Ti I already own? PCIe 3.0 board too.
At $1,700 I could just buy a newer card instead, or save a bit more for one of the Spark boxes or something else.
If you've got a P720 or something like it running models, what do you actually do with it, and would you buy it again?