RTX 5070 vs RTX 4080 for LLMs: New Architecture or More VRAM?
The RTX 5070 brings NVIDIA Blackwell architecture at $549 but keeps 12 GB VRAM. The RTX 4080 is last-gen but offers 16 GB VRAM for around $750 used. For LLM inference, VRAM is often the bottleneck, making this a question of architecture speed vs raw memory capacity.
Verdict
NVIDIA RTX 4080 (16 GB)The RTX 4080 with 16 GB VRAM runs larger models and longer contexts than the RTX 5070 with 12 GB. The RTX 5070 is faster per token on models that fit. For LLM inference specifically, VRAM matters more than architecture generation. Buy the 4080 used if you can find one at a good price.
NVIDIA RTX 5070 (12 GB)
2
wins
Ties
0
draws
NVIDIA RTX 4080 (16 GB)
3
wins
Category-by-Category Breakdown
Detailed Analysis
VRAM
NVIDIA RTX 4080 (16 GB)4 GB more VRAM means the 4080 can run 14B Q4 models that do not fit on the 5070. For LLMs, VRAM is the most important spec.
NVIDIA RTX 5070 (12 GB)
12 GB GDDR7
NVIDIA RTX 4080 (16 GB)
16 GB GDDR6X
Memory Bandwidth
NVIDIA RTX 4080 (16 GB)The RTX 4080 has higher effective bandwidth for AI workloads due to its wider memory bus, despite the 5070 using newer GDDR7.
NVIDIA RTX 5070 (12 GB)
448 GB/s (GDDR7)
NVIDIA RTX 4080 (16 GB)
717 GB/s
Speed on 7B Models
NVIDIA RTX 4080 (16 GB)The 4080 is slightly faster on models that fit in both cards VRAM, thanks to higher memory bandwidth.
NVIDIA RTX 5070 (12 GB)
~50-60 tok/s
NVIDIA RTX 4080 (16 GB)
~55-65 tok/s
Price (New)
NVIDIA RTX 5070 (12 GB)The 5070 is cheaper new. But used 4080s at $600-700 offer better value for AI workloads.
NVIDIA RTX 5070 (12 GB)
$549 MSRP
NVIDIA RTX 4080 (16 GB)
$750-900 used / discontinued new
Power Efficiency
NVIDIA RTX 5070 (12 GB)The 5070 uses less power, which matters for always-on inference servers.
NVIDIA RTX 5070 (12 GB)
250W TDP, newer architecture
NVIDIA RTX 4080 (16 GB)
320W TDP
Frequently Asked Questions
Is 12 GB VRAM enough for LLMs in 2025?
Should I buy RTX 5070 or used RTX 4080 for AI?
Can either card run 30B models?
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