Overclocking muddies waters for Nvidia's redesigned RTX 4090 and US sanctions

Cut-down chips get a big boost

US sanctions on China that banned Nvidia's fastest gaming GPU might be irrelevant thanks to overclocking its slightly slower replacement back to original levels of performance.

While the RTX 4090 was initially approved for sale in China, the October update to export restrictions banned the GPU from being sold there. Nvidia then created the RTX 4090D, a slightly cut-down version of the 4090 with 11 percent less cores, allowing it to just barely duck under the 4,800 total processing performance limit. In the end, the 4090D is only about 5 percent slower than the 4090, according to some benchmarks.

Technically, the RTX 4090D supports overclocking and could be made faster, but a major obstacle for overclocking with the initial batch of 4090D chips was that there seemed to be no way to adjust the maximum power consumption limit of 425 watts, which the 4090D already runs at by default.

However, Asus's new ROG Strix model of the RTX 4090D shows that this power limit isn't set in stone and can actually be adjusted, according to a source in China HKEPC. Per a Google translated version of the review, "the TGP power consumption can be liberated from 100 percent 425W to the highest 141 percent 600W," a 41 percent boost.

It's not entirely clear from these initial tests if the 4090D couldn't increase power beyond the default 425 watt power limit because Nvidia and its partners intended for it to not be adjustable, or because overclocking applications hadn't yet updated for the 4090D. Either way, at least one model now appears to be truly overclockable.

In HKEPC's review, increasing the power limit to 600 watts increased performance by 3.2 percent in the standard 3DMark Speed Way test and then adding in a relatively modest 200MHz GPU and 187MHz memory overclock boosted speed by 9.3 percent. Considering that the overclocked 4090D only peaked at 558 watts, there may be room for even more improvements.

If you've been keeping score, you might notice that this level of performance is actually on par with the regular 4090, if not better. Granted, we're talking about single digit percentage points, but these small numbers are the difference between the 4090 being banned and the 4090D being legal.

Overclocking has never been especially relevant to GPU sanctions since the initial round only impacted datacenter cards, which generally don't support such speeding up methods. However, the ban of the RTX 4090 and the introduction of the RTX 4090D may bring overclocking to the US government's attention - it seems like a really big loophole.

Though, GPU export restrictions aren't set on gaming performance, but hinges on floating point performance, which is determined by both regular CUDA cores and tensor cores. After all, the US government is concerned about Nvidia GPUs, even the RTX 4090, being used for AI work. It's not entirely clear if a realistic overclock on just the CUDA cores could push the 4090D over the limit and into the realm of sanctioned performance levels.

Still, the idea of overclocking to bypass sanctions may irritate US Commerce Secretary Gina Raimondo, who hasn't been on the best terms with Nvidia and its series of made-for-China GPUs.

"I'm telling you, if you redesign a chip around a particular cutline that enables them to do AI, I am going to control it the very next day," she said in a fireside chat last December. While this comment was walked back later, it seems unlikely she will be amused by the idea of sanctions being bypassed by simply increasing a card's clock speed. ®

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