Re: REQ: recomendations for barebones number crunching/OpenGL machine

B Thomas <thomasb@xxxxxxxxxxxxxxxxxxx> wrote:
> I am looking to assemble or buy a barebones number crunching
> machine that has accelerated opengl graphics support. I would
> not want to use any binary only drivers (such as nvidia) at all.

Unfortunately, this leavs you with low-end cards like Radeon 9250 only if
you want stable opensource drivers.

> If you have built anything similar I would be very greatfull
> for your experience and any advise you have to offer.

I have configured some number crunching machines, but it was more than a
year ago, so might be able to get more up-to-date advices from others. I
don't have any own experience from dual core CPUs or PCI-express in number
crunching machines.

> I don't see any point using a 64 bit pc as it is only the
> integer bit that is different and lots of numerical software
> did not anticipate 64 bit machines so are quite buggy to use.

Both the AMD Opteron CPUs and Intel Xeon CPUs support 64 bits today, but
that doesn't mean you have to use it. A 32 bit OS still works fine as long
as you don't intend to use more than 4 GB of RAM.

> I look for ward to you recomendations for
> Motherboard, cpu and video card.

For video card I would have to recomend a low-end Radeon 9250. Those are
the best ones with stable OpenGL support from the opensource drivers.

For motherboard I would recomend an Asus NCCH-DL which is made for dual
Xeon CPUs. It differs from many other server motherboards as it is built
upon the 875 chipest which gives you an AGP port. You didn't say anything
about SMP, but for number crunching SMP can mean twice the performance.

If you instead prefer AMD CPUs I would probably choose a Tyan Thunder K8W.
It is a dual opteron board with AGP. I have no experience from that board
myself. I once did choose between that board and an Iwill board. I did
select the Iwill board but have had some troubles with it so today I would
try the Tyan board instead.

The choice between Xeon or Opteron depends on your application. Things
to consider:

An Opteron aproximately 1.5 times as fast as a Xeon with the same clock
speed.

A good quality Opteron motherboard have a memory bank of its own for each
CPU. This gives better bandwidth than a single memory bank which almost
every Xeon motherboard has.

Xeon has hyperthreading. This means that a single CPU core can fake that
it is two CPUs by letting the fake CPU use parts of the real CPU that
currently is unused. For most applications this gives better performance.
This means that two single-core Xeons will look like four CPUs to the
operating system. Two double core Xeons will look like eight CPUs to the
OS.

Some chipsets limit the amount of usable RAM for a 32 bit OS to about 3
GB. With i875 chipset I have been able to use 4 GB with 32 bit Linux, but
our Opteron server is only able to use about 3 GB.

regards Henrik
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