Does anyone ship a working PC under $4000 with four quad-cores? I
really don't care at all about RAM or disk or graphics, I just need
CPU. My Core-2 Duo has spent the past six weeks running two random
number tests. That's a typical load for me.
Four sockets implies a server sized motherboard. Four high end quad
processors would likely eat up the $4000 by themselves.
You can get an idea of the technical capabilities of the various
options here. In terms of sockets, there are some older AMD K8
products, with 8 sockets times dual-core each. So that would give
a 16 core system, but note that to get 8 cores, there are two motherboards
strapped together by Hypertransport riser cards. The thing weighs
a ton, uses a monster power supply (>1000W), and the end price when equipped
with RAM, would be *way* above where you want to be.
http://www.tyan.com/tech/product_matrix.aspx
The Intel stuff all seems to be dual socket, and that has to
do with how the processors are connected together.
http://www.supermicro.com/products/motherboard/Xeon1333/?chp=5000P
In a previous generation, the concept was to use a shared FSB
bus. Of course that doesn't scale well, for obvious reasons.
A secondary issue, is signal integrity. The more sockets you
use, the worse looking the signals get on a shared bus, and
the slower the FSB has to run, to work.
The solution was, to put private interfaces on the Northbridge.
The 5000 chipset has two FSB interfaces on it, one for each
socket. The interconnect electrically is point to point, and
can run much faster - the signals would be very good looking.
That allows the sockets to run at FSB1333. And that
is what makes owning a quad core make sense, as it is less
starved for memory bandwidth. If the quad core didn't have FSB1333,
you wouldn't get as much speedup from it.
This is an example of a previous product. (Note - I wasn't able to
find a block diagram of the architecture, and it could actually be
using a combination of multiple FSBs and shared busses.)
This has four sockets, but at FSB667. The second link shows a
typical price. IBM apparently makes its own chipsets for Intel
processors. But trying to find something to buy on the IBM site,
is a daunting task. (The Tyan and Supermicro products are
generally based on chipsets they can buy on the open
market. IBM can make their own chipsets, being IBM and all.)
http://www5.pc.ibm.com/europe/products.nsf/$wwwPartNumLookup/_88641RG?OpenDocument
http://www.cdw.com/shop/products/default.aspx?edc=988271
http://www.theregister.com/2005/02/22/ibm_hurricane_chipset/
This is another way to do your shopping. Look for four sockets
in this list, and see who sells them.
http://www.spec.org/cpu2006/results/cpu2006.html
When the cores are running your application, do they do their
calculation "in private", without sharing data structures ?
In other words, would "cluster computing" be more appropriate,
with a bunch of cheaper processors working on a section of the
problem at a time ? When you say you "don't really care at all"
about RAM, that tells me the problem is self contained, and
perhaps four single socket motherboards, each with a quad-core
CPU, would do the job. Or eight single socket motherboards each
with a dual core processor.
Also, if your evaluation project is of fixed duration, maybe
you could buy computing time on a large server somewhere.
Paul
