Dual-CPU Computer-Buying Advice Sought

[by]

Ladies and Gentlemen:

I am planning on buying two computers in the near future, one
with the taxpayer's money and one on my own dime, for my research use.
The workstation that currently stands in my office looks like this:

2xAthlon MP 2000+ (1.67GHz); 2x1GB+2x512MB registered ECC DDR2100 DIMMs;
Tyan S2466 (760 MPX, integrated NIC, no working USB ports); Seagate 80GB
7200rpm HDD; Advansys UltraSCSI; 40x CD-ROM; Plextor 12x10x32x SCSI CD-RW;
VIA's USB 2.0 PCI card; NIC (Realtek 8139); NVidia GeoForce 2MX 64MB.

I run Linux and have been spoiled by dual-CPU machines -- I've
built a total of 9 dualies since 1996 when the linux 2.2 kernels came
out. Running linux or sometimes WinNT, they have served me (as well as
the friends who were gifted or bought the used machines) very well. I
run mainly Maple, some gcc-compiled binaries, and LaTeX. The programs
I run often end up having gigabytes-sized arrays, hence the RAM size.

When planning the upgrade, the most comprehensive advice I got
googling for "hardware-buying advice" was the following list:

Dan J. Bernstein's recommended "standard workstation"

$240 2xAthlon MP 2400+ (Thoroughbred 2.0GHz)
$92 Western Digital Caviar 120GB "Special Edition" 8MB buffer 7200rpm
$189 Gigabyte GA-7DPXDW-P (760 MPX for Athlon MP, integrated NIC)
$120 Kingston 512MB ECC DDR2100 DIMM
[a bunch of other stuff including Antec case and a 450W power]

That's $641 (NewEgg prices); a nice case + power plus assorted odds and
ends raises the entire pricelist up to around $870; I can reuse my other
peripherals: I swear by IBM's trackpoint Mechanical M13 keyboard and its
other trackpoint items, and two screens at each work location. If I am
going to fill the machine to 3 GB, that will set me back a further $800
for $1600 for the entire machine.

If I buy instead a pair of Opteron 240's for $200 each and Tyan's S2885
(Thunder K8W) for $450 each, that will set me back a further $400+, for
about $2000 for the whole machine. Opteron 246's are a hefty $650 each
so that will cost me about $3100 for this entire workstation.

Is this a good buy for my office machine?

Are Opteron 240's better or worse for my purposes than Athlon MP 2800's?
2600's? Would Xeon's be any good at all? How about my home machine? I
want it to have significant computing power although I may not need that
much memory at home ... Thanks in advance for any advice ...

 

[Nate Edel]

the friends who were gifted or bought the used machines) very well. I
run mainly Maple, some gcc-compiled binaries, and LaTeX. The programs
I run often end up having gigabytes-sized arrays, hence the RAM size.

If you need 3gb of ram, seriously consider going with Opterons. You'll be
glad you did. Linux high memory support works well if you have a single
process address space, but it'll start costing you once you have anything
else running.

If I buy instead a pair of Opteron 240's for $200 each and Tyan's S2885
(Thunder K8W) for $450 each, that will set me back a further $400+, for
about $2000 for the whole machine. Opteron 246's are a hefty $650 each
so that will cost me about $3100 for this entire workstation.

Is this a good buy for my office machine?

That doesn't quite add up; that looks like it will add up to $2900 for the
whole machine if the Dual 240 is $2000 (~$450 extra for each 246, x2).

Are Opteron 240's better or worse for my purposes than Athlon MP 2800's?
2600's?

IGNORING the x86-64 support.

Advantages of the Opteron: 300% higher memory bandwidth (dual channel 400FSB
vs single channel 266FSB), much reduced memory latency, ~2x or ~4x cache
(are there any Barton-based Athlon MPs?), slightly better core. Plus the
processor-matched memory on the better dual Opteron boards will give you
effectively _four_ channels.

Advantages of the Athlon MP: much higher core speeds at a given price point.

A 2ghz Athlon MP is going to beat a 1.4ghz Opteron on purely arithmetic
benchmarks as long as they stay in-cache, but the higher memory bandwidth
and bigger cache will likely make a bigger difference in office-use and
software development workloads. And TeX will likely feel snappier on the
Opteron.

GIVEN that you're working with > 1gb arrays, you get the Opteron anyway. It
will run much more nicely with that much physical memory, if you also run a
64-bit kernel.

Would Xeon's be any good at all?

Better memory bandwidth than the Athlon MP, not as good as the Opteron;
crappy netburst architecture with high core speeds. Depends on your
workloads... _IF_ your code is not branchy and is optimizable for
P4/Netburst well -- especially if it's vectorizable -- Xeon will wipe the
floor with the Athlon MP, and beat the Opteron handily.

MOST code, however, doesn't adapt nearly so well to Netburst.

How about my home machine? I want it to have significant computing power
although I may not need that much memory at home ... Thanks in advance for
any advice ...

If you go with the Opterons at work, go with the Opterons at home, or drop
to a single and get a 146 or a Athlon 64 3200+.

You might consider going with one of the cheaper dualie boards (with memory
on only one of the two processors) for your home system; saves about $200,
and while it costs you memory bandwidth, it is still going to outperform a
dual based on a shared-bus architecture (like the Athlon MP or Xeon)
especially given the FSB difference.

 

[RusH]

(are there any Barton-based Athlon MPs?),

hmm any AMD XP processor can be turned into MP

Pozdrawiam.

 

[Nate Edel]

hmm any AMD XP processor can be turned into MP

*lol* They never closed that loophole?

Aside from that, though, what I was asking was whether any of the current
sold-as-Athlon-MP models were 512k cache versions based on the core that's
called Barton when sold as an Athlon XP.

 

[by]

*lol* They never closed that loophole?
Aside from that, though, what I was asking was whether any of the current
sold-as-Athlon-MP models were 512k cache versions based on the core that's
called Barton when sold as an Athlon XP.

Yes, the athlon mp 2800+ is a 2.08 GHz barton on a 266 buss

but the 2800 is significantly more costly than the 2600

is anyone else offering any opinions on the merits/demerits of the opteron
boards vs. the athlon boards?

 

[Rob Stow]

Yes, the athlon mp 2800+ is a 2.08 GHz barton on a 266 buss

Note that this is also an excellent, but expensive, processor
for those of you with single processor 266 MHz FSB motherboards.
Only moderately overclockable.

but the 2800 is significantly more costly than the 2600

is anyone else offering any opinions on the merits/demerits of the opteron
boards vs. the athlon boards?

Yes. Moi !

I have built three Opty dualies using the Tyan S2885
and one using the S2875. In the past I also built a
few Athlon dualies (both XP and MP) and even one Duron
dualie.

I would suggest that if you already have an Athlon dualie,
then upgrading it may be a reasonable thing to do.

However, if you are building a dualie from scratch, I would
suggest you forget Athlons and go with Opterons. Depending
on which components you would use in an Athlon dualie versus
which you would use in an Opteron dualie, an Opty dualie
can range from just a tad more expensive to a whole lot more
expensive.

However, the low end of the Opty dualie range, such as a
pair of Opty 240's on an S2875 will compete nicely with the
high end of the Athlon MPs, such as a pair of MP2800's on
the motherboard of your choice. Additionally, the Athlon
MP2800 solution puts you at an immediate dead end, whereas
the Opty 240 (1.4 GHz) dualie can be upgraded to at least
the Opty 248 (2.2 GHz) that is currently available and it
should also be OK with the Opty 252 (2.6 GHz)we are apparently
supposed to see by the end of the year.

Note also that the economics of a new Athlon MP system vs a
new Opty system are one thing, but used kit is quite another.
There are some excellent bargains to be found in the way
of used Athlon dualie motherboards and Athlon processors.
Used Opterons are also starting to show up as people who began
with Opty 240's or 242's are starting to find that upgrades to
Opty 246 and 248 have become feasible now that prices have
come down a bit.

 

[Nate Edel]

Yes, the athlon mp 2800+ is a 2.08 GHz barton on a 266 buss
but the 2800 is significantly more costly than the 2600
Gothca.

is anyone else offering any opinions on the merits/demerits of the opteron
boards vs. the athlon boards?

As has been said before, one of, if not _the_ biggest difference is memory
bandwidth.

The Athlon MP boards have ~2.2 gigabytes per second bandwidth shared by both
CPUs; one of the better (with per-cpu memory) newer-stepping Opteron boards
has ~6.4 gigabytes per second per CPU.

Memory latency is better on the Opteron boards, thanks to the on-board
controller. Caches are twice the size of the Athlon MP 2800 or four times
the size of the 2600+. The 8131/8151 chipset is a LOT more up to date than
the 760MP/MPX.