They were trying to compete with Sun and IBM in the server space (SPARC and Power) and thought that they needed a totally pro architecture (which Itanium was). The baggage of 32-bit x86 would have just slowed it all down. However having an x86-64 would have confused customers in the middle.
Think back then it was all about massive databases - that was where the big money was and x86 wasn't really setup for the top end load patterns of databases (or OLAP data lakes).
In the end, Intel did cannibalize themselves. It wasn’t too long after the Itanium launch that Intel was publicly presenting a roadmap that had Xeons as the appealing mass-market server product.
Yeah they actually survived quite well. Who knows how much they put into Itanium but in the end they did pull the plug and Xeons dominated the market for years.
They even had a chance with mobile chips using ATOM but ARM was too compelling and I think Apple was sick of the Intel dependency so when there was an opportunity in the mobile space to not be so deeply tied to Intel they took it.
I think the difference was that replacing Itaniums with Xeons on the roadmap didn't seriously hurt margins (probably helped!)
The problem with mobile was that it fundamentally required low-margin products, and Intel never (or way too late) realized that was a kind of business they should want to be in.
> and thought that they needed a totally pro architecture (which Itanium was).
Was it though ? They made a new CPU from scratch, promissing to replace Alpha, PA-RISC and MIPS, but the first release was a flop.
The only "win" of Itanium that I see, is that it eliminated some competitors in low and medium end server market: MIPS and PA-RISC, with SPARC being on life support.
The deep and close relationship of Compaq with Intel meant that it also killed off Alpha, which unlike MIPS and PA-RISC wasn't going out by itself (Itanium was explicitly to be PA-RISC replacement, in fact it started as one, while SGI had issues with MIPS. SPARC was reeling from the radioactive cache scandal at the time but wasn't in as bad condition as MIPS, AFAIK)
I never used them but my understanding is that the performance was solid - but in a market with incumbents you don't just need to be as good as them you need to be significantly better or significantly cheaper. My sense was that it met expectations but that it wasn't enough for people to switch over.
Merced (first generation Itanium) had hilariously bad performance, and its built in "x86 support" was even slower.
HP-designed later cores were much faster and omitted x86 hardware support replacing it with software emulation if needed, but ultimately IA-64 rarely ever ran with good performance as far as I know.
Pretty sure it was Itanium that finally turned "Sufficiently Smart Compiler" into curse phrase as it is understood today, and definitely popularized it.
Think back then it was all about massive databases - that was where the big money was and x86 wasn't really setup for the top end load patterns of databases (or OLAP data lakes).