According to the latest info from the Chiphell forums, AMD’s Radeon RX 6600 XT is about to arrive in the next 60 days or so. The rumor alleges that the RX 6600 XT will feature 2,048 stream processors (cores) paired with 8GB of GDDR6 memory across a 128-bit bus. Its non-X sibling, the RX 6600 will feature the same memory and bus, but a reduced core count of 1,792 shaders. Both the GPUs will leverage the Navi 23 die, the successor to Navi 14.
In comparison, the Radeon RX 5600 XT was based on the same die as the RX 5700 and 5700 XT, namely Navi 10, with the same core count as the former. The only difference was with respect to the bus width (192-bit vs 256-bit) and the boost clocks. In terms of the L3 (Infinity Cache), you can expect 64MB of it on both GPUs.
The source has also provided the TimeSpy performance figures of the two GPUs. While the 6600 XT is a fair it faster than the RX 5700 XT, the 6600 ends up performing slightly faster than the RX 5700. This means we can expect the 6600 XT to be a good 30-40% faster than the RX 5600 XT, with more memory to boot.
In terms of pricing (although irrelevant at this point), you can expect a launch price of around $300, just a smidge less than the RTX 3060.