RTX 5090 vs RTX 4090: Which GPU Is Better for AI Workloads?
For local AI workloads, the RTX 5090 is the stronger GPU: it offers 32 GB of GDDR7 memory and 1792 GB/s of memory bandwidth, compared with 24 GB of GDDR6X and 1008 GB/s on the RTX 4090, per NVIDIA's specifications. The RTX 4090 is the cheaper card at MSRP and still runs the same workloads with less headroom. How much that headroom matters depends on the models you run. Best overall for AI: RTX 5090. Best for budget-minded 24 GB workloads: RTX 4090. Specs checked August 14, 2026.
How do the specifications compare?
The RTX 5090 leads on every capacity and bandwidth metric, while the RTX 4090 costs less at MSRP and draws less power. The full specification comparison is below, per NVIDIA's specification pages for both cards.
| Specification | GeForce RTX 5090 | GeForce RTX 4090 |
|---|---|---|
| VRAM | 32 GB | 24 GB |
| Memory type | GDDR7 | GDDR6X |
| Memory bus | 512 bit | 384 bit |
| Memory bandwidth | 1792 GB/s | 1008 GB/s |
| Total board power (TDP) | 575 W | 450 W |
| CUDA cores | 21760 | 16384 |
| MSRP | $1,999 | $1,599 |
| PCIe interface | PCIe 5.0 x16 | PCIe 4.0 x16 |
| Architecture | Blackwell | Ada Lovelace |
Which GPU has more VRAM, and why does it matter for AI?
The RTX 5090 has 32 GB of VRAM; the RTX 4090 has 24 GB, per NVIDIA's specifications. VRAM capacity decides which AI models fit on the card without offloading to system memory, so the extra 8 GB is the single biggest difference between these two GPUs for AI work.
For small models such as Llama-3-8B at Q4 quantization, both cards hold the model comfortably, and capacity is not the limiting factor. For larger models such as Llama-3-70B at Q4, capacity becomes critical. According to Tom's Hardware testing, the RTX 5090 runs Llama-3-70B at 42 tokens per second with a tight fit in 32 GB, while the RTX 4090 manages 18 tokens per second in 24 GB with heavy swapping, a result flagged as a rough estimate precisely because the card runs out of room. In practice, the RTX 5090's 32 GB turns 70B-class models from a struggle into a workload that fits, and it also gives image generation pipelines more room for large batches and high-resolution latents.
Which GPU is faster for LLM inference?
The RTX 5090 is faster: it serves Llama-3-8B at Q4 quantization at 320 tokens per second in llama.cpp, versus 220 tokens per second on the RTX 4090, according to Tom's Hardware testing. Both results come from the same benchmark source and software stack, so they are directly comparable.
The gap comes from raw memory and compute resources. The RTX 5090 pairs its 32 GB of GDDR7 with 1792 GB/s of bandwidth and 21760 CUDA cores; the RTX 4090 offers 1008 GB/s across 24 GB of GDDR6X and 16384 CUDA cores, per NVIDIA's specifications. Token generation on a single GPU is largely bound by memory bandwidth, which is why the bandwidth advantage carries directly into inference throughput.
Which GPU is faster for image generation?
The RTX 5090 generates SDXL Turbo images at 120 images per minute in ComfyUI, versus 80 images per minute on the RTX 4090, according to Tom's Hardware testing. If you produce images in volume, the RTX 5090 finishes the same batch in less time.
Image generation also benefits from spare VRAM when you queue multiple images or run upsampling passes alongside the base model. The RTX 5090's 32 GB gives that headroom; on the RTX 4090's 24 GB, large batch queues are more likely to force smaller batches per run.
Which GPU costs less?
At launch MSRP, the RTX 4090 costs less: $1,599 versus $1,999 for the RTX 5090, per NVIDIA's announced pricing. MSRP is not street price — availability moves real prices in both directions, so check current price via the links below before deciding.
We deliberately avoid computing performance-per-dollar ratios: the right denominator depends on your workload mix, and street prices change too often for derived value math to stay honest. The benchmark numbers above, attributed to their sources, let you judge value against whichever price you actually find.
How much power does each GPU need?
The RTX 5090 has a 575 W total board power rating; the RTX 4090 is rated at 450 W, per NVIDIA's specifications. That power difference affects your power supply sizing, case airflow, and how much heat the system dumps under sustained AI loads.
Both cards need a case and cooler rated for a flagship GPU, and a power supply with comfortable headroom above the board power rating. Sustained LLM inference and image generation hold the GPU near its power limit for hours, so cooling that would be fine for intermittent gaming loads can become the limiting factor for AI batch work.
What are the disadvantages of each GPU?
Neither card is a free win: the RTX 5090 costs and consumes more, while the RTX 4090 gives up capacity and speed. The specific trade-offs follow.
RTX 5090 disadvantages:
- Higher MSRP: $1,999 versus $1,599 for the RTX 4090.
- Higher power draw: 575 W versus 450 W total board power, per NVIDIA's specifications.
- Requires cooling and a power budget that many existing builds cannot supply without upgrades.
RTX 4090 disadvantages:
- Less VRAM: 24 GB versus 32 GB, which caps comfortable model sizes below the 70B class.
- Lower memory bandwidth: 1008 GB/s versus 1792 GB/s, which shows up directly in tokens per second.
- Slower on every tracked benchmark in our database, including the 18 tokens per second Llama-3-70B result flagged as a rough estimate.
Who should buy the RTX 5090, and who should buy the RTX 4090?
Buy the RTX 5090 if you run models near or above the 24 GB limit, or if throughput is your constraint: 70B-class models at 42 tokens per second and 120 SDXL Turbo images per minute justify the price for anyone whose time is worth money. Buy the RTX 4090 if your models fit in 24 GB, your budget is tighter, or your power and cooling ceiling is closer to 450 W than 575 W.
Best for 70B-class LLM work and heavy image generation: RTX 5090. It is the only one of the two that holds Llama-3-70B at Q4 without heavy swapping, according to Tom's Hardware testing.
Best for cost-conscious 8B-to-30B model work: RTX 4090. It still delivers 220 tokens per second on Llama-3-8B, and its $1,599 MSRP undercuts the RTX 5090 by $400.
How did we compare these two GPUs?
We compared the RTX 5090 and RTX 4090 using only two classes of evidence: manufacturer specifications and published benchmark results tracked in our benchmark database. Specifications (VRAM, memory type, bus width, bandwidth, board power, CUDA cores, PCIe interface, architecture, MSRP) come from NVIDIA's specification pages. Benchmark numbers come from Tom's Hardware GPU Benchmarks 2025, our tracked source for these two cards, using identical model, quantization, and software stack settings within each comparison. We publish no derived ratios and no street prices; where a result is an estimate in the source data, we say so. Facts checked August 14, 2026.
Frequently Asked Questions
These are the questions buyers actually ask when choosing between the RTX 5090 and RTX 4090 for AI work.
Is the RTX 5090 worth it over the RTX 4090 for AI?
If you run 70B-class models or batch image generation, yes: the RTX 5090's 32 GB of VRAM and 1792 GB/s of bandwidth change what fits and how fast it runs, per NVIDIA's specifications and Tom's Hardware testing. If your models fit in 24 GB, the RTX 4090 at a $1,599 MSRP is the saner buy.
Can the RTX 4090 run Llama-3-70B?
Yes, but not comfortably. According to Tom's Hardware testing, the RTX 4090 runs Llama-3-70B at Q4 at 18 tokens per second with heavy swapping in its 24 GB, and that figure is flagged as a rough estimate in the source data. The RTX 5090 runs the same model at 42 tokens per second with a tight fit.
Does the RTX 5090 use a lot more power than the RTX 4090?
Yes. The RTX 5090 is rated at 575 W total board power versus 450 W for the RTX 4090, per NVIDIA's specifications. Plan the power supply and cooling accordingly.
Is the RTX 5090 faster than the RTX 4090 at Stable Diffusion image generation?
Yes. According to Tom's Hardware testing, the RTX 5090 produces 120 SDXL Turbo images per minute in ComfyUI versus 80 on the RTX 4090. The RTX 5090 also has more VRAM headroom for large batch queues.
Do both GPUs support PCIe 5.0?
No. The RTX 5090 uses a PCIe 5.0 x16 interface; the RTX 4090 uses PCIe 4.0 x16, per NVIDIA's specifications. For single-GPU AI inference, the interface difference matters far less than VRAM and bandwidth.
Which GPU has more memory bandwidth?
The RTX 5090, with 1792 GB/s across a 512 bit bus on GDDR7, versus 1008 GB/s across a 384 bit bus on GDDR6X for the RTX 4090, per NVIDIA's specifications. Bandwidth is the main driver of single-GPU token generation speed.
Sources
Specification and benchmark claims in this article come from the following origins.
- NVIDIA GeForce RTX 5090 and GeForce RTX 4090 official specification pages (manufacturer specifications).
- Tom's Hardware GPU Benchmarks 2025 — Llama-3-8B and Llama-3-70B Q4 llama.cpp tokens per second, and SDXL Turbo ComfyUI images per minute: https://www.tomshardware.com/pc-components/gpus
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