A number of times now an LCS version of the Radeon RX 6900 XT has surfaced on the web. This round in Asia it got tested en benchmarked. The GPU is XTXH based, the fastest 6900 SKU, but all that cooling and binned GPU results in merely 5% extra performance. 

Benchmarks surfaced at Bilibili which seems to be the Sapphire 'reference model' with XTXH GPU. The normal RX 6900 has a maximum boost clock of 2,250 MHz, the water-cooled variant would be able to reach 2.435 MHz. The frequency of the memory has also been increased, to 18.48 Gbps.

3DMark benchmarks shows an added 5 percent performance over the reference model. To compare, a Sapphire RX 6900 XT Toxic Extreme Edition scores 2 to 4 percent higher, thanks to its higher clock speeds. It is not clear if and when this card will be released to the piblic. Likely it'll only be fitted for prebuilt systems. 

Update, clock have been confirmed as well. 12% Higher Core and Memory Clocks, 10% Higher Power. The card game clocks is 2250 MHz, (2015 MHz reference air), memory is at 18 Gbps (GDDR6 effective), compared to 16 Gbps for reference which is 576 GB/s opposed to 512 GB/s on the reference card. TBP (total board power) has been increased by 10%, and is 330W. All this yields roughly 5% extra perf.

LCS Radeon RX 6900 XT Benchmarks 12% faster Core and Memory Clocks with 10% more power