Nvidia slowed RTX 4090 GPU by 11 percent, to make it 100 percent legal for export to China

For now

Nvidia's GeForce RTX 4090 GPU is back on sale in China – in a less capable configuration version designed to comply with US restrictions on exports into the Middle Kingdom.

Dubbed the RTX 4090D, the device appeared on Nvidia's Chinese-market website Thursday and boasts performance roughly 10.94 percent lower than the model Nvidia announced in late 2022. This shows up in the form of lower core count, 14,592 CUDA cores versus 16,384 on versions sold outside of China.

Nvidia also told The Register today the card's tensor core count has also been been cut down by a similar margin from 512 to 456 on the 4090D variant. Beyond this the card is largely unchanged, with peak clock speeds rated at 2.52 GHz, 24 GB of GDDR6x memory, and a fat 384-bit memory bus.

As we reported at the time, the RTX 4090 was the only consumer graphics card barred from sale in the Middle Kingdom following the October publication of the Biden Administration's most restrictive set of export controls.

The problem was the card narrowly exceeded the performance limits on consumer cards with a total processing performance (TPP) of more than 4,800. That number is calculated by doubling the max number of dense tera-operations per second — floating point or integer — and multiplying by the bit length of the operation.

The original 4090 clocked a TPP of 5,285 performance, which meant Nvidia needed a US government-issued license to sell the popular gaming card in China. Note, consumer cards aren't subject to the performance density metric that restricts the sale of much less powerful datacenter cards like the Nvidia L4.

As it happens, cutting performance by 10.94 percent is enough to bring the card under the metrics that trigger the requirement for the USA’s Bureau of Industry and Security (BIS) to consider an export license.

While slower Nvidia insisted the performance his is much less than you might think.

"In 4K gaming with ray tracing and deep-learning super sampling (DLSS), the GeForce RTX 4090D is about five percent slower than the GeForce RTX 4090 and it operates like every other GeForce GPU, which can be overclocked by end users," an Nvidia spokesperson said in an email.

The fact that the card can be overclocked means that conceivably some performance lost by the lower core count could be recovered by customers willing to do a bit of tinkering.

This isn't the first time Nvidia has nerfed the performance of its graphics cards to comply with US export controls. In late 2022, following a wave of restrictions on the sale of AI accelerators in China, the American giant cut down the interconnect speed of its popular A100 units and relaunched it as the A800. The card was followed by a new version of the H100, predictably called the H800. (Eight is the luckiest number in Chinese numerology: the naming of the A800 and H800 was no accident.)

The fresh round of export restrictions announced in October saw Nvidia again deliver chips designed for the Chinese market. The L2, L20, and H20 limbo danced right under Washington’s performance caps.

Nvidia's antics quickly caught the attention of US Commerce Secretary Gina Raimondo who warned chipmakers against testing those bans. "I'm telling you, if you redesign a chip around a particular cut-line that enables them to do AI, I am going to control it the very next day," she said during a forum in early December.

Raimondo later told Reuters the Commerce Department was working closely with Nvidia to ensure that GPUs and AI accelerators that pose a threat to US national security weren't sold to China, but that the chip house could and should be able to do business there. ®

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