NVIDIA GeForce RTX 4090M/4080M “Frankenstein” desktop graphics cards tested

PRO Hi-Tech bought two desktop gaming cards equipped with NVIDIA’s top GPUs for laptops.

NVIDIA did not plan for gamers to use RTX 4090M and RTX 4080M in desktop PCs. However, these mobile graphics cards are widely available in China for desktop upgrades. Despite the risk, users opt for them due to their lower prices compared to high-end desktop GPUs.

The popularity of mobile GPUs in desktop form factor has grown in the past few years, mainly due to cryptomining boom. Such GPUs often bought in bulk were sold to many Chinese companies that were never an official NVIDIA partner. The mobile GPUs are said to be from defective laptop motherboards that were supposed to be destroyed, but have ended up at auctions where they are bought and GPUs are unsoldered.

RTX 4080M & RTX 4090M, Source: PRO Hi-Tech

NVIDIA Mobile on Desktop GPUs

• Lower price
• Better power efficiency
• Worse specs compared to desktop variants
• Lack of official support from NVIDIA
• Potential problems with the drivers
• Potential physical damage to the GPU die
• Potential problems with the warranty

GPU-Z detection for RTX 4090M, Source: PRO Hi-Tech

The process of adapting mobile GPUs to desktop PCBs isn’t overly complex. Thanks to their lower power requirements, these cards don’t require premium power sections or powerful cooling systems. This makes them an attractive option for repurposing unsold GPUs for less demanding users.

PRO Hi-Tech procured samples of the RTX 4090M and RTX 4080M graphics cards mentioned earlier in January. These relatively new cards, exclusive to the China market, share identical power requirements, resulting in identical PCBs and cooling solutions.

Upon dismantling the cards, the reviewer made two discoveries. Firstly, they found that the GPU die was cracked, indicating that the chips likely originated from defective parts or were mishandled during production. While small cracks typically don’t immediately damage the GPU, prolonged exposure to excessive heat during intensive GPU sessions could lead to unpredictable outcomes.

Cracked GPUs, Source: PRO Hi-Tech

Secondly, the chips were labeled as “QUAL SAMPLE” (qualification), indicating that they were not even retail-grade chips. This suggests that these GPUs were intended for testing and quality assurance purposes rather than consumer use. How they ended up in these cards is unclear.

In terms of performance, the RTX 4090M is equivalent to a desktop RTX 4080. The RTX 4080M should perform as desktop RTX 4070Ti. However, power consumption remains relatively low, comparable to that of a regular 4070 Ti. The reviewer proceeds to test rendering and cryptomining.

RTX 4090M & 4080M in Cyberpunk 2077, Source: PRO Hi-Tech

The RTX 4090M and RTX 4080M highlight the trade-off between cost and quality. While these cards offer a more budget-friendly option, the visible damage to the GPU die may deter many gamers from ever considering them. However, some may still be willing to take the risk for the sake of affordability.

For gamers, having alternatives is always beneficial, but the absence of official support is a significant drawback. Officially supported hardware ensures compatibility and reliability, along with access to necessary updates and optimizations. Unfortunately, these cards lack such support, making their usage a gamble for those who choose to adopt them.

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