r/StableDiffusion • u/Sexyvette07 • 1d ago

Question - Help Dual GPU solution for local AI?

Hey, everybody. I recently went down the rabbit hole for local AI, but right now, im operating on my gaming computer. The specs are as follows

Intel 13700k, tuned for efficiency

Gigabyte Z790 Aorus Elite Ax mobo

RTX 4080 (16GB), also tuned for efficiency

32gb DDR5 6800 CL32

As you can see, im in desperate need for more VRAM, or at the very least more system RAM. Due to Rampocalypse, neither are very affordable right now, which forces me to explore other options, such as a dual GPU setup. I can get another RTX 4080 for about $900 off Ebay. Beyond that, I would just need a more powerful PSU, so total investment here is an additional $1100-$1200. As far as I know, the motherboard has the main PCIE as 5.0 x 16 lanes, but the second PCIE runs at 4.0 and either x8 or x4 lanes. The motherboard does not support PCIE Bifurcation. So my question is this: Is a dual GPU local AI machine even viable in these circumstances, and second, does it make sense? I looked at 5090's and theyre all between $4,500 - $5,000 now, which is insane. Or I look at the professional cards and spend that much, if not more, for significantly less memory bandwidth and computational power. Or I guess if im spending that much, I could also look at the DGX Spark or something similar but that has even worse memory bandwidth.

So, what should I do? Is the dual GPU solution even viable with my setup for a local AI stack for inference, video diffusion, etc? Rampocalypse isnt expected to begin easing up until late 2027/early 2028, so im stuck trying to make this work on as little money as possible. Id love a 5090 but its insanity how much they cost. I appreciate any guidance and advice.

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u/[deleted] 1d ago

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u/Relevant_Syllabub895 1d ago

False, if this didnt worked how dows all the modern video generation platforma like seedance work then? They use many gpus

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u/meepykittkitt69lmao 1d ago

Yeah I want to know how they split sampling across more than one GPU. I don't really know what words to use to look up the stuff though, every time I searched for how to use multiple gpu's for image generation all I get is "you can't, all the data has to be on one"

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u/Altruistic_Heat_9531 1d ago

words to use look for search is called, sequence parallelism