Ask Slashdot: Finding Quad Pentium II Motherboards?

Another member of Clan Anonymous Coward writes in with this question: "I have been looking for a quad pII board but have yet to actually find one. If you know where I can find one, send me an email to wakko@animx.eu.org. Please send all 'pII's sucks amd rocks' messages to /dev/null."

Comments

Wont find it - here's why:

[Anonymous Coward]

To answer your question, yes, it is possible to have a four way SMP machine using the Pentium II processor but you wont find such a motherboard. The CPU is not the limiting factor, it's the motherboard "core logic" chipset. Quick review:

Intel 440LX supports one or two Pentium II CPUs (slot 1) with a 66MHz front side bus. Chipset is features an SDRAM memory controller and a dual PCI bridge - one 33Mhz 32 bit PCI, and one 66Mhz 32 bit AGP with 2x mode.

Intel 440BX supports one or two Pentium II CPUs (slot 1) with a 66 or 100MHz front side bus. Chipset features an SDRAM memory controller and a dual PCI bridge - one 33MHz 32 bit PCI, and one 66MHz 32 bit AGP with 2x mode.

Intel 440NX supports up to eight Xeon CPUs (slot 2) with a 100MHz front side bus. Chipset features a four way interleaved SDRAM controller and a dual PCI bridge - one 66MHz 32 bit PCI, and one 33MHz 64 bit PCI. NO AGP!

Now, the first two chipsets are the "cheap" consumer variety. The third chipset is the expensive server variety which is fairly obvious as it supports up to 8 CPUs, four way memory interleave, and offers a 64 bit PCI bus. The trade off is that you don't get an AGP slot - but that isn't needed on a server anyway. It's also intended for slot 2 (Xeon) CPU's. Now, technically, you could design a board with the NX chipset that supported 4 slot 1 CPUs - but there probably wouldn't be much of a market - and Intel doesn't want you to do that anyway. (They might not sell you the chipset at all if they thought you were going to use it for slot 1 designs.)

$4k for a good quad Sparc/Alpha/whatever?

[Christopher Thomas]

Then call SGI, Sun, IBM, and Alpha retailers, and see what you can get for the same money. Check Memory I/O, Mega/Giga-flops, SPECS, and I think you will see, we're not playing in Intel's field anymore.

I studied these companies' offerings in detail about a month ago, when I wondered how much a really _good_ multiprocessor system costs.

The answer is about $30k+ for something like a quad box, and about $100k+ for something with more respectable performance.

I've heard people quote high single-digit $k for Alpha boxen, but I'm still suspicious as to what's on the motherboard.

From what I found, both IBM and SGI had horrible price/performance ratios (for what I was looking for; my primary concern was FP performance). Sun systems were ok, but the real winner from what I could tell was HP. They sell PA-RISC 8500 boxen with large numbers of processors and respectable cache for a (relatively) reasonable price. They have a pricing sheet on their web site, though you have to dig a fair bit for it. Some of the manufacturers give Spec figures, but it's still a good idea to stop by spec.org to find out what the performance of some of the boxen listed actually ends up being.

What I concluded from the survey was that I'm better off spending $10k (Canadian) and buying 15 K62-400 boxen. The problems that I want to solve are easily compartmentalized.

SMP vs Clustering

[Christopher Thomas]

The main problem here is communications latency and bandwidth. In a SMP box, it's easy for the processors to communicate large amounts of data to each other and to have a fast communications response time. It's also (relatively) easy to perform shared memory accessing and to arbitrate memory locking.

A cluster, OTOH, has to stuff all inter-processor communications through a network cable. This works quite well for easily compartmentalized problems that don't need much access to shared memory. However, if you had a large chunk of memory that you wanted each processor to be able to do more or less random locking, reading, and modification on, your network will go into meltdown. Especially if this memory is distributed over many boxes (i.e. each box contains a part of the very large whole instead of each box mirroring all of a smaller shared memory block).

Myself, when I buy the machine of my dreams, I'll probably go the clustering route. There are plenty of problems that I'd like to play with that don't have unreasonable communications loads, and it is one heck of a lot cheaper to build a cluster for something like that than to pay through the nose for big iron (or even medium-sized aluminum).

chipset issue

[IntlHarvester]

Note that you can buy a "Pentium Pro Overdrive" chip, which is essentially a 333Mhz Xeon that fits in a PPro socket.

I doubt they're much cheaper than the regular Xeons, but you'd be able save some money on the motherboard.
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