Is There a 48GB RTX 5090? No: What to Buy Instead
People search for a 48GB RTX 5090 because 32GB is just short of a 70B model at 4-bit. The card does not exist. NVIDIA lists the RTX 5090 with 32GB of GDDR7, and no working 48GB mod has been shown in public. This page says what the rumours actually are, and which cards give you 48GB today.
Bottom Line
- No. NVIDIA’s RTX 5090 is 32GB GDDR7. NVIDIA sells no 48GB GeForce card.
- The “5090 48GB” in the news is a prediction. It came from 3GB GDDR7 chips going on sale in China. Nobody has shown a working card.
- The mods that got written up are 96GB and 128GB. Neither is confirmed. The 96GB listing reportedly says GDDR6X, which a 5090 cannot use.
- The cheapest real 48GB is two used RTX 3090s, about $2,000 for the pair as of September 2026.
- The odd 2026 fact: a stock 32GB RTX 5090 now costs more than a used 48GB RTX A6000.
Why People Want 48GB
The number that matters is a 70B model at 4-bit. llama.cpp measures its Q4_K_M format at 4.89 bits per weight. That gives:
70B weights x 4.89 bits / 8 = about 42.8 GBThis is our arithmetic, not a download size. Add the KV cache on top. The result fits in 48GB. It does not fit in 32GB without offloading layers to system RAM, and offloading cuts token speed hard.
So the search is reasonable. A 5090 with 48GB would be the fastest 70B card a person could buy. It just is not for sale.
What Actually Exists
| Claim | Status (September 2026) | Evidence |
|---|---|---|
| Official 48GB RTX 5090 | Does not exist | NVIDIA product page: 32GB GDDR7 |
| Modded 48GB RTX 5090 | Prediction only | VideoCardz: Samsung 3GB GDDR7 modules on sale in China, “48GB mods incoming?” |
| Modded 96GB RTX 5090 | Unconfirmed listing | Tom’s Hardware: Alibaba listing at $3,888; listing text reportedly says GDDR6X at 14 Gbps |
| Modded 128GB RTX 5090 | Called debunked | Tom’s Hardware covered a $13,000 “prototype”; a Hardware Canucks forum thread calls it debunked |
| RTX 5090 Ti / TITAN Blackwell | Rumour | Reported for Q3 2026 by multiple outlets; no datasheet, no memory size confirmed |
| Modded 48GB RTX 4090 (“4090D 48G”) | Real, sold in China | Clamshell PCB, custom BIOS, no warranty; VideoCardz reports a water-cooled version |
The 4090 mod is the reason people expect a 5090 mod. The method is known: move the GPU die to a board that holds twice the memory chips, then flash a custom BIOS. The 5090 needs 3GB GDDR7 chips and working firmware for that. The chips now exist. Public proof of working firmware does not.
Do not pay for a modded card you cannot return. A mod has no NVIDIA warranty, and a card that fails on a driver update is a very expensive paperweight.
The Real 48GB Routes
| Route | VRAM | Memory | Price as of September 2026 | Best for |
|---|---|---|---|---|
| 2x used RTX 3090 | 24GB + 24GB | GDDR6X | about $2,000 for the pair | Lowest cost per GB |
| Used RTX A6000 | 48GB, one card | GDDR6, 768 GB/s | about $4,370 (gpudojo tracker) | One quiet 2-slot card |
| RTX PRO 5000 Blackwell | 48GB, one card | GDDR7 ECC, 300W | $9,199+ on Newegg marketplace | Blackwell features, one card |
| 1x RTX 5090 (for contrast) | 32GB | GDDR7, 1,792 GB/s | far above the $1,999 MSRP; check listings | Speed on models under ~28GB |
Prices come from scraped trackers and marketplace listings, so treat them as indicative. They move week to week.
Two used 3090s are the value pick. You split the model across two cards, and both runtimes that matter (llama.cpp and vLLM) do this well. The costs are power, heat and a board with two x16-sized slots.
Check RTX 3090 prices on Amazon
A used RTX A6000 is the one-card pick. Its 768 GB/s GDDR6 is slower per token than a 3090 pair. In exchange, it is one card in one slot, and a second one later gives you 96GB.
Check RTX A6000 48GB prices on Amazon
The RTX PRO 5000 Blackwell is the new-card pick. At marketplace prices above $9,000 it is hard to justify for one person, and the RTX PRO 6000 at 96GB is the better step up at that spend.
Check RTX PRO 5000 Blackwell 48GB on Amazon
Should You Just Buy a 32GB 5090?
Buy the 5090 if your models fit in 32GB. It is the fastest single card for models of about 28GB or less, because its memory bandwidth is 1,792 GB/s (28 Gbps GDDR7 on a 512-bit bus). That covers the 27B-35B class at 4-bit with room for context.
Do not buy it as a 70B card. At 42.8GB of weights, a 70B model spills into system RAM, and your token speed drops to what the RAM path allows. Two used 3090s run the same model fully on GPU for less than half the price.
Sources
- NVIDIA GeForce RTX 5090 product page (32GB GDDR7, 512-bit, 575W), read 2026-09-13
- VideoCardz: Samsung 3GB GDDR7 modules available in China, “RTX 5090 48GB mods incoming?”
- Tom’s Hardware: China-modified RTX 5090 with 96GB on Alibaba for $3,888; 128GB RTX 5090 “prototype” at $13,000
- Hardware Canucks forum: “Modded RTX 5090 with 128GB of VRAM debunked”
- VideoCardz: water-cooled GeForce RTX 4090 48GB mods, sales booming in China
- Newegg: RTX PRO 5000 48GB listing (48GB GDDR7 ECC, 300W, $9,199 marketplace), read 2026-09-13
- gpudojo RTX A6000 tracker (768 GB/s, $4,370 used), read 2026-09-13
- bestvaluegpu RTX 3090 price history (used ~$972-1,050), September 2026
- llama.cpp
tools/quantize/README.md(Q4_K_M 4.8944 bits per weight)
See Also
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