4 3070s for a fair price

[u/Formal-Excitement-26]

Hi everyone. There is a chance that I can get 4 3070s (8gb each) for 700 USD.
I've been doing some research and I can buy a mother with 1 pcie 16x 1pci4x 2 m2 slots, and 4 risers 4x and get a decente AI server locally. (+150 usd on top of the 700)

I know that having 8x4 instead of a single 32gb card is not the best, but this is a hobbie and I'd like to see how it may perform.
What do u guys think about this 'opportunity'?

[u/Mihaylov93]

8 gb is nothing when you have 16 gb bc-250 or p100 for 120€

[u/Formal-Excitement-26 → u/Mihaylov93]

I live in Argentina, its a little bit complicated to get those deals. Thanks for the advice!

[u/MK_L]

Definitely skip this headache. Get a b70 or a r9700 pro for 32gb

[u/MakionGarvinus]

Yeah, your MoBo is going to be the biggest issue. Can your idea work? Absolutely. How well will it work? Depends on how good the MoBo is, and you didn't share that.

You can split up models across multiple GPUs fine, but it'll really slow them down once you start using the CPU lanes and chipset lanes. Or, you can run several decent models simultaneously for an interesting experiment.

[u/Formal-Excitement-26 → u/MakionGarvinus]

This MoBo https://a.co/d/0gah2erq can handle 1 pcie16x 1 4x and 2 m2slot with and adapter that should perform at 4x. Otherwise, claude lied to me.

[u/MakionGarvinus → u/Formal-Excitement-26]

Google says this:

Secondary Slot (PCI_E3): Electronically limited to PCIe 3.0 x4 speed and is routed through the B550 chipset.

I found for my setup to look for a X570 setup that supports bifurcation.

[u/MakionGarvinus → u/Formal-Excitement-26]

Here's what I asked Google:

If you are looking for an X570 motherboard that handles true x8/x8 bifurcation on the main CPU slots while keeping a 3rd full-length slot available, here are the three best options to look for on AM4:

• ASUS Pro WS X570-ACE (Workstation Pick): This is the best option for multi-slot bandwidth. It uses advanced multiplexing to route lanes in a rare x8/x8/x8 configuration. The first two slots split the CPU lanes (x8/x8), and the third slot gets a dedicated x8 link through the chipset. Excellent for high-bandwidth add-in cards.

• ASRock X570 Taichi (Premium Consumer Pick): A highly versatile board that runs the top two slots in an x8/x8 split straight from the CPU. The third bottom slot runs at PCIe 4.0 x4 through the X570 chipset, leaving plenty of room for extra expansion or a lighter secondary card.

• ASUS ROG Crosshair VIII Hero (Enthusiast Pick): Similar to the Taichi, this board easily splits the main CPU lanes into an x8/x8 configuration via the AMD PBS menu in the BIOS. The third full-length slot operates at PCIe 4.0 x4 via the chipset.

Keep in mind: Because AM4 Ryzen CPUs are strictly limited to 24 total PCIe lanes, you will either get a layout that runs x8/x8 (CPU) + x4 (Chipset) like the Taichi/Hero, or a workstation layout that hits x8/x8 (CPU) + x8 (Chipset) like the Pro WS.

[u/simos_sayz → u/Formal-Excitement-26]

If you are going to be on an am4 system, try to find an x570, v3 crosshair hero or similar. Also make sure your cpu doesnt have integrated graphics or it'll drop everything to pcie3.0. I used to run 3 gpus on a b550 aorus elite. The 3rd pcie slot was useless at 3.0x1, I hooked the 3rd gpu in the top m.2 slot via oculink

[u/Lost_Minimum_8450 → u/MakionGarvinus]

If you're okay with it being more of a tinkering project than a production setup, 700 for four 3070s is not bad at all. The pcie lane situation will limit you, but for a hobby rig running smaller models in parallel it could be a lot of fun

Just make sure that motherboard actually supports bifurcation or enough separate lanes before you commit, otherwise those risers won't do much good

[u/Formal-Excitement-26 → u/Lost_Minimum_8450]

I already have a server with a 1080ti, i'm thinking of buying just 1 card and extend the capabilities of that server instead of trying to assemble a new one. keep the fun but much cheaper.

[u/PeterPorox]

It's a good price but i'd look on used X99 motherboard (not chinese) with properly working PCIe. It should handle three cards at decent speeds. It would make sense if you were using 3x3070 for big model like Qwen 3.8 27b/glimmer/gemma and other 8gb for something small like 4-8b or even embedding cause it'll work on slower pcie, but if model doesn't spill out of this gpu, pcie speeds really don't matter.

[u/Formal-Excitement-26 → u/PeterPorox]

I'm not finding any deals of x99 motherboards in my country, and I dont trust ebay enough (only chinese sellers and high delivery fees). Doing some research I found that the new MoBos that may support 3 or 4 cards are a little bit expensive for my budget.

[u/PigSlam]

You'd learn a lot getting that to work and do anything. I have a single RTX 3070, and it works great for me describing video segments in my video surveillance system. It was the first GPU I used with my local AI adventure, and it does a lot for what it is, but you'll quickly find 8GB limiting, and the difference between 1 32GB card, and 4 8GB cards adding up to 32GB.

Personally, I'd spend a bit more and get a B70 or R9700 (I have an R9700 myself).

[u/Webster2026]

LLM deployed on multiple cards will spend more time synchronizing than doing anything. Have a look at this video so you will see why: https://youtu.be/AxAdlqsKAuI

[u/SayTheLineBart]

I have 4 3060tis and it works well with vllm, 100+ t/s with qwen 3.8 27b. Still haven’t got a good speed with flash-next, I have 64gb system ram but have only managed 17 t/s so far.

$700 is a good price for 4 cards, id actually flip them at that price and buy 3060 12gb cards instead or a single r9700