In brief: The US government's ban on Nvidia exporting its RTX 4090 to China looks like it's been removed. Restrictions on high-performance GPUs and AI accelerators have come into effect earlier than announced, but the flagship gaming card is missing from the list of affected products. Rumors that the US was set to further tighten export restrictions on AI accelerators to China proved accurate last week when the Department Bureau of Industry and Security updated the rules. Restrictions on communication speeds, limited to a bidirectional transfer rate of 600 GB/s, were removed; instead, priority was given to those products with…