Pentium II Xeon Motherboards
The only motherboard manufacturer shipping Xeon motherboards right now is Intel. I ran my tests on Intel's 'Marlinspike' MS440GX workstation dual Xeon motherboard, based on the 440GX chipset. For servers Intel is offering two bare bone solutions, including the chassis as well as the motherboard. You can choose between the AD450NX quad CPU killer server platform or the more modest SC450NX quad CPU server platform, both based on the 450NX chipset.
Performance Expectations, a Word on Multi-Processing and Multi-Threading
What shall we expect from a Pentium II Xeon? Will it blow away all that we knew so far?
The answer is yes and no. In the first place it's got to be a 'no', since the Pentium II Xeon won't blow away the Pentium II at all on the usual platforms where the Pentium II is used so far. The CPU core of the Xeon is identical to the core of the Pentium II as well as the Celeron, so the difference is only produced by the different L2 cache. In single processing and single threaded applications the performance gain of a full speed L2 cache over the half speed L2 cache of the Pentium II is minimal. Thus we will hardly see any difference in ANY application under Windows 95 or Windows 98. These two toys OSes are a simple 'no-go' for the Pentium II Xeon, because none of them supports multi processing or multi-threading. It requires a multi processing 32 bit OS like Windows NT or UNIX to take the slightest advantage of Xeon. The full speed L2 cache can show its muscles only when both CPUs are working hard, so even in a multi-processing or multi-threading environment where the CPUs are idle for half or 30% of the time the difference between Pentium II and Pentium II Xeon will be very little.
That is why it takes well programmed multi-threaded workstation software to show the benefit of the Xeon in workstation environments. The performance gain through the second CPU can be between 30 and 95 %, but this 'can be' is valid for both, the Xeon as well as the Pentium II. Only heavy traffic on the memory bus will give the full speed L2 cache of the Xeon an advantage, so that dual Xeon system can be between 3 - 25% faster than a dual Pentium II system.
The story looks a lot different in server systems. Here the Pentium II cannot compete because it's not up to running in quad configurations anyhow. A heavily working server has always got full traffic on the memory and I/O buses. Here the Xeon shows its power. It scales almost linearly with the amount of CPUs used and whilst a Pentium II or Pentium Pro server shows a serious drop in TPS (transactions per second), the Xeon can still go ahead and kick some serious butt.
If you want to understand more about multi-processing and multi-threading, please have a look at this excellent paper from Intel.