Quote Originally Posted by informal View Post
Start from X6 score,apply 33% more cores ,no scaling penalty and normalize for 3.2Ghz clock : 5.91x1.33x3.2/3.3=~7.62pts. This is the hypothetical score of Zambezi X8 that would show ZERO IPC improvement in C11.5 Vs Thuban. Now compare with "blogger's" result of 7.37pts : 7.37/7.62=0.96pts or 4% IPC decrease per core Vs Thuban. Hmm,fishy indeed .
This is simple:
Theoretical max. 128b FMUL+FADD throughput of Zambezi w/o using FMA is the same as of a X4 per clock. So based on this it should perform lower. But CB is no synthetic benchmark (FMUL+FADD loop) and depends on a lot of other components. And as it is known it isn't that dependent on memory throughput due to data locality. So Zambezi's IMC shouldn't have much influence here.