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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallFor local AI, the RTX 3090 and RTX 4090 have the same 24 GB of GDDR6X memory, so the 4090 does not let you load a larger model solely by virtue of its VRAM capacity. NVIDIA lists more CUDA cores and a newer architecture for the 4090, but the available evidence does not establish a universal local-AI speed advantage or a current value winner. Choose by testing your actual model and settings, then weigh that throughput against price, power, and system compatibility.
RTX 3090 vs. RTX 4090 at a glance
| Specification | RTX 3090 | RTX 4090 | What it means for local AI |
|---|---|---|---|
| Architecture | Ampere | Ada Lovelace | A generational difference, not a workload benchmark. |
| CUDA cores | 10,496 | 16,384 | More cores do not translate directly into a predictable end-to-end speed ratio. |
| Memory | 24 GB GDDR6X | 24 GB GDDR6X | The headline capacity is tied; usable model capacity also depends on runtime overhead and settings. |
| Reference graphics-card power | 350 W | 450 W total graphics power | Reference figures only; check the exact add-in-board model. |
| Recommended system power | 750 W | 850 W | NVIDIA guidance for reference configurations, not a universal PSU-sizing rule. |
Specifications are from NVIDIA’s RTX 3090 product page and RTX 4090 product page. Board-partner cards can differ in dimensions, cooling, connectors, and power targets.
| # | Preview | Product | Price | |
|---|---|---|---|---|
| 1 |
|
VIPERA NVIDIA GeForce RTX 4090 Founders Edition Graphic Card | $4,440.00 | Buy on Amazon |
| 2 |
|
ASUS TUF Gaming GeForce RTX™ 5080 16GB GDDR7 OC Edition Graphics Card | $1,831.31 | Buy on Amazon |
How much faster is the RTX 4090 for local AI?
There is no supported universal multiplier for local-AI performance. NVIDIA’s launch announcement described the RTX 4090 as offering up to 2x performance in then-current games and up to 4x in full ray-traced games using DLSS 3, compared with the RTX 3090 Ti. Those were gaming claims under specified rendering conditions—not local-AI results, and the comparison card was a 3090 Ti rather than a 3090. See NVIDIA’s 2022 RTX 40 Series announcement.
A secondary local-AI GPU comparison reports memory bandwidth of 936 GB/s for the RTX 3090 and 1008 GB/s for the RTX 4090, and notes that bandwidth can affect generation speed after a model fits. Its llama.cpp rows are sourced measurements; other rows are estimates based on memory bandwidth and model size. Treat those estimates as estimates, not measured results or a general speed ratio.
#1 Best Overall
- 16,384 NVIDIA CUDA Cores
- Supports 4K 120Hz HDR, 8K 60Hz HDR and variable refresh rate as indicated in HDMI 2.1A
- New streaming multiprocessors: up to 2x power and power efficiency
- Fourth generation tensor cores: up to 2x AI power
- Third-generation RT cores: up to 2x ray tracing performance
For a useful comparison, run the same model, quantization, context length, batch size, runtime and version on both cards. Record the workload and settings alongside any tokens-per-second result. Different choices can change both model fit and throughput, so a result from one configuration may not predict another.
Do both GPUs fit the same local-AI models?
For headline memory capacity, yes: NVIDIA lists 24 GB of GDDR6X on each card. That makes them candidates for the same broad model-fit class, but it does not guarantee that a particular model or configuration will fit. The memory available to model weights is reduced by runtime allocations, context or KV cache, batch size, operating-system and display use, and other GPU workloads.
The secondary comparison’s tracked-model table reports the same count of models fitting on each card under its Q4 classification. That finding applies to its selected model set and methodology; it is not a promise that every model, quantization, context, or runtime will work on either GPU.
Before buying, check the memory requirement for the exact model and configuration you plan to run. Leave room for context and runtime overhead rather than treating the full 24 GB as available for weights.
Power, cooling, and physical fit
NVIDIA specifies 350 W reference graphics-card power and recommends a 750 W system power supply for the RTX 3090. For the RTX 4090, NVIDIA lists 450 W total graphics power and an 850 W system-power recommendation. These are manufacturer figures for reference configurations; verify the requirements of the specific board and the rest of your system.
Before choosing a card, confirm the following against the manufacturer’s specifications for that exact model:
Rank #2
- Powered by the NVIDIA Blackwell architecture and DLSS 4. System Requirements: Minimum 850W PSU with 16-pin 12V-2x6 (12VHPWR) connector required. Verify before purchasing.
- Military-grade components deliver rock-solid power and longer lifespan for ultimate durability. Compatibility: 348mm (13.7") length, 3.6 slots, 4.3 lbs. Confirm case clearance and slot spacing. GPU bracket included.
- Protective PCB coating helps protect against short circuits caused by moisture, dust, or debris
- 3.6-slot design with massive fin array optimized for airflow from three Axial-tech fans
- Phase-change GPU thermal pad helps ensure optimal thermal performance and longevity, outlasting traditional thermal paste for graphics cards under heavy loads
- Power-supply capacity and the card’s required power connectors.
- Case clearance, including card length, height, and slot thickness.
- Cooling capacity and airflow for sustained workloads.
- Whether other components or GPU uses affect power and memory headroom.
NVIDIA’s Ada architecture paper says its reference RTX 4090 design achieves 20% more airflow than the RTX 3090. This is a vendor-reported comparison of reference cooler design; it does not establish the cooling or noise behavior of every partner card. See NVIDIA’s Ada architecture paper.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Which card is the better value?
A current value winner cannot be named without comparable regional prices and workload-matched results. NVIDIA announced the RTX 4090 at $1,599 at launch in September 2022; that historical launch price is not a current retail price or a comparison with today’s RTX 3090 listings.
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Compare the cards using the costs and results that apply to your situation:
- Current price, card condition, seller terms, and warranty or return coverage.
- Measured throughput on your intended workload using matching model and inference settings.
- Whether the card has enough VRAM headroom for your context length and batch size.
- Power use during that workload and electricity cost, if relevant to your use.
- Any additional system changes needed for power, connectors, dimensions, or cooling.
If you already own an RTX 3090
Evaluate an upgrade by comparing the measured improvement on your own work with the net cost after selling or keeping the 3090. The available specifications and comparisons do not establish a universal upgrade threshold; your workload and local prices decide whether the change is worthwhile.
If you are choosing between the two
Start with the exact board models and current offers, not NVIDIA’s old launch price. If both meet your model-fit needs, benchmark the workload that matters to you and include any power or system upgrade costs before deciding.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
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