Pentium vs. Xeon vs. Itanium

Ok I would like to have a few things cleared up, and im sure some of the others would as well. Basically this is a comparison of Intels desktop CPU, server CPU, and bigger server? CPU.

Now I'm comparing Intels but the same goes for AMD.

What is the difference between a desktop CPU, a server CPU, and w/e the hell the Itanium is for?

*The highest end desktop CPUs are the conroes clocking in at 2.8Ghz Dual core with a shared L2 cache of 4MB and a FSB of 1066Mhz. $1000

**The highest end server CPU is the Xeon 5080 clocking in at 3.7Ghz Dual core with 2 X 2MB of L2 cache and a FSB of 1066Mhz. $876

***The highest end Itanium that will be coming out (w/e it is for) is the Itanium 9050 clocking in at 1.6Ghz Dual core with a whoping 24MB of L3 cache and a FSB of 533Mhz. $3700

Now I believe the Xeon is the older architecture that the Pentium Ds were based on, which is why its clock speed is so much faster than the conroe, even tho the conroe would out perform it (I believe..)

Why use the Xeon or the Itanium when the Conroe is faster (I believe) and has the same amount of cores? And the Itanium looks like a pretty bad CPU from the specs and cost almost 4 grand?! What is L3 cache exactly and how is it different than L2?

Thanks for any info you can provide, as this has always confused me!!!

Conroe Processors
The new range of desktop processors is based on the Pentium M design track rather than the Pentium track, but using 65nm technology. Core Solo and Core Duo are already out, but do not support EM64T. Core 2 Duo will be released officially next week and will support EM64T. Conroe is the codename for Core 2 Duo processors. They have very good processor performance, which is let down by relatively poor memory access. In addition, when running in 64-bit mode they have some poor Floating Point features in comparison to AMD64 processors. They do not allow pci devices dma access to memory above 4GB, a feature wich will probably be of little concern to desktop users but is significant to high end servers.

Xeon processors
They are effectively multi-processor capable, high specification versions of the equivalent Pentium. They are the A++ extracts from QC, and consequently should run cooler and be more reliable than the lower versions. They started life as the replacement of the Pentium Pro - the Pentium II Xeon. Subsequent models also simply had Xeon tagged on the end, then later they were simply called Xeon processors. Now that the Pentium has effectively been dropped it is hard to see what the direct replacement will be.

Itanium processors
These are full 64bit processors developed jointly by Intel and HP. They are not compatible with x86 architecture. They use what is called Explicitly Parallel Instruction Computing (EPIC). In standard architectures the chip "guesses" what the result of a comparison will be, and preloads the subsequent instructions accordingly. That's fine if most guesses are correct, but performance suffers badly when the guess is wrong. With EPIC the compiler makes the guesses, but also provides preload for when the guess is wrong, thus offering a good performance boost.

Alright thanks for the info man. I still have a couple of questions.

What enviornment would the Itanium be the best choice...what is it used for in the real world?

And the Xeon can have 2 CPUs on one board where as the Conroe can only have 1 per board, correct? And what exactly do you mean they are the A++ extracts from QC?

Thanks for your info man!

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Originally Posted by bigdawgfoxx

Alright thanks for the info man. I still have a couple of questions.

What enviornment would the Itanium be the best choice...what is it used for in the real world?

And the Xeon can have 2 CPUs on one board where as the Conroe can only have 1 per board, correct? And what exactly do you mean they are the A++ extracts from QC?

Thanks for your info man!

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Itanium processors are used exclusively for servers.

There are ports of Windows 2000, XP and Server 2003, along with many server apps, but no client apps. Longhorn will be supported.

Various implementations of Linux support it, and HP-UX was available right from the start. Sun ported Solaris to it, but soon dropped it. Likewise SCO worked with IBM to port AIX across, but it never saw the light of day.

There are several other implementations, but few if any are likely to be of much interest to the home user.

I'm sure multi-chip versions of Conroe must be in the pipeline, but they already have 2 cores to the Xeon's one, and run cool too. I expect there will be a Xeon version before long.

All chips of a particular architecture are made using the same process, and are then tested and graded. Obviously some will fail completely. After that, their performance rating depends on how well they did in the test. The poorer ones become the lower speed chips, the better ones become the higher speed chips. Obviously there will be more poor ones that good ones so the price varies accordingly.

The best chips (what I've called A++) are reserved for special purposes. In the ordinary market they would be capable of higher speeds than most, often better than the top of the range chips. Because of their reliability and cool running they are given a lower speed but called Xeon chips which boosts their value.

Good info, that cleared up quite a few questions I've had for some time:happy;

Ohhh ok...so a xeon is just a more reliable version of the desktop cpu..or is what I understand to be correct at least lol.

The whole Itanium thing is confusing to me kinda, but so is the purpose of servers.

Thanks for clearing it up for me (and others im sure too)!