Wouldn't factor in the D just yet, even the 4090D is specced higher than the 5080:
The mem bandwidth and bus width speak for themselves really It's not like the core architecture is very different to gain performance via efficiency either here.
If the 5080 is similar performance to a 4090D then the RTX 5090 should be somewhere between 50-60% faster than a 4090 and that is some speed increase. This is all assuming everything scales linear, which it does not. Anything is possible I suppose.
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