One thing to remember is that FP performance with well-scheduled code was by far its strongest performing area, and Intel put a lot of work into tuning their compiler for those specific tests. The problem was that it fell off heavily the less your code is like that, especially for the branchy code most business apps depend on.
The other big problem was that the x86 compatibility story was worse than the earlier hopes. That meant that it not only wasn’t competitive with the current generation competition but often even the previous or worse - note losing to the original Pentium or even a 486 here:
Now, they could have improved that but statistically nobody was going to pay considerably more for lower performance in the hopes that a future update would improve matters.
The Athlon and Opteron weren’t just fast, they also had flawless 32-bit support so even if your 64-bit software update never happened you could justify the purchase based on their price/performance.
The other big problem was that the x86 compatibility story was worse than the earlier hopes. That meant that it not only wasn’t competitive with the current generation competition but often even the previous or worse - note losing to the original Pentium or even a 486 here:
https://tweakers.net/reviews/204/8/intel-itanium-sneak-previ...
Now, they could have improved that but statistically nobody was going to pay considerably more for lower performance in the hopes that a future update would improve matters.
The Athlon and Opteron weren’t just fast, they also had flawless 32-bit support so even if your 64-bit software update never happened you could justify the purchase based on their price/performance.