Running Stable Diffusion and Flux locally is mostly a VRAM problem, and the number that decides everything is 24 GB. A digital artist running Stable Diffusion and Flux at full quality needs a single NVIDIA card with 24 GB of VRAM, because that clears both the comfortable Stable Diffusion working range and the demanding FP16 footprint of Flux.1 Dev on one card. Nail the GPU and the rest of the machine comes together logically; miss it and you spend your days fighting quantisation instead of making art.
Quick Answer
Target a 24 GB NVIDIA GPU. That is the threshold that runs Flux.1 Dev at full FP16 quality with room left for ControlNet and LoRAs, while SDXL and SD 3.5 run with ease. An RTX 4090 with 24 GB is the practical choice for professional-grade local work, paired with a modern CPU, 32 GB or more of system RAM, and a fast NVMe drive. SA builds for this start above the R8,000 entry tier and climb with the GPU.
Why 24 GB is the line that matters
Image models are sized by precision. Flux.1 Dev needs around 24 GB at FP16, the full-quality mode, drops to roughly 12 to 15 GB at FP8 or Q8, and squeezes into 6 to 8 GB at heavily compressed Q4. Stable Diffusion's modern variants are lighter but still reward headroom once you stack ControlNet, multiple LoRAs and high resolutions.
The reason an artist wants the full 24 GB is quality and freedom. At FP16 you are running the model as intended, with no quantisation artefacts and enough spare memory to layer the control tools that make local generation genuinely useful for production. Drop below that and you are forced to quantise Flux, which trades fidelity for fit. The RTX 4090's 24 GB is the only consumer-class card that runs Flux Dev at FP16 without that compromise, which is why it anchors a serious artist's rig.
Building around the GPU
The GPU does the work, but a balanced build keeps it fed and stops bottlenecks elsewhere.
System RAM and CPU
A figure of 32 GB of system RAM is the sensible working minimum for this kind of machine. Model loading, image post-processing and running a creative app like Krita or Photoshop alongside your generation tool all draw on it, and 16 GB gets tight fast. The CPU does not need to be extreme; a current mid-to-upper mainstream processor handles loading, preprocessing and the broader pipeline without holding the GPU back. Spend the budget on VRAM first, then RAM, then CPU.
Storage and the model library
Models are large and you will collect many of them. A Flux checkpoint alone runs into the tens of gigabytes, and once you add SDXL, SD 3.5, refiners, LoRAs and your output folder, capacity disappears quickly. An NVMe SSD of 1 TB or more is the sensible floor, both for room and because loading a multi-gigabyte model from a quick drive is far less painful than from a slow one. The current GPU options that drive these builds sit in the GPU best sellers, a useful view of which 24 GB cards are shipping right now.
Generation speed and workflow
On the RTX 4090, Stable Diffusion XL generates at roughly 3 seconds per image and Flux Dev at full FP16 takes around 18 seconds at standard step counts. Those numbers shape a workflow: SDXL for fast iteration and Flux for final-quality renders. Once you know the rhythm, having both models available at native precision rather than quantised fallbacks changes how freely you can work.
What it costs and where to start in SA
A capable local-AI art rig sits well above the R8,000 entry laptop tier, because the GPU alone is the bulk of the cost. The honest framing for an SA buyer is to treat the 24 GB GPU as the anchor purchase and build a sensible machine around it rather than chasing a top-end CPU you will not use for inference. If your budget cannot reach a 24 GB card yet, a 16 GB GPU still runs Flux at FP8 and handles SDXL well, which is a workable starting point. Evetech's AI PC range covers purpose-built machines that carry the memory and cooling these workloads demand.
Who this build is for
This is the rig for an illustrator, concept artist or designer who wants to generate, refine and iterate locally rather than paying per image in the cloud, and who values full FP16 quality and the ability to run ControlNet and LoRAs freely. If you only dabble occasionally, a 16 GB card with FP8 Flux is enough. If image generation is part of how you earn, the 24 GB card pays for itself in speed, quality and the freedom to run the tools without compromise.
Frequently Asked Questions
How much VRAM do I really need for Flux locally?
Flux.1 Dev needs about 24 GB at full FP16 quality, which is why a 24 GB GPU is the target for serious work. You can run it at FP8 on 12 to 15 GB, or at heavily compressed Q4 on 6 to 8 GB, but those trade fidelity for a smaller footprint.
Is the RTX 4090 overkill for a digital artist?
Not if you want full quality. Its 24 GB is the only consumer-class option that runs Flux Dev at FP16 without quantisation, with room for ControlNet and LoRAs, so it is the practical choice for professional-grade local generation rather than overkill.
Can I run Stable Diffusion and Flux on 16GB?
Yes, with caveats. SDXL and SD 3.5 run comfortably on 16 GB, and Flux runs at FP8 there too, but you lose full FP16 quality and some headroom for stacking control tools. It is a solid starting point you can later upgrade from.
How much RAM and storage should the rest of the build have?
Target a minimum of 32 GB of system RAM and an NVMe SSD of 1 TB or larger. Models are large, you will collect many of them, and post-processing alongside a creative app uses real memory, so both keep the GPU fed and your library on hand.
Do I need a top-end CPU for AI image generation?
No. Generation runs on the GPU, so a current mid-to-upper mainstream CPU is plenty for loading models and preprocessing. Put the budget into VRAM and RAM before chasing the fastest processor.
If local Stable Diffusion and Flux are part of how you create, build around a 24 GB GPU and the rest follows. Explore the machines made for it in the Evetech AI PC range and size your rig to the quality you actually want.