How does this budget number cruncher look?

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nerd249

Hi guys. I'll be buying a few of these PCs for number crunching with a
tight personal budget. My university has a parallel cluster but it is
saturated with jobs at the moment. At least having my own parallel
cluster would mean I have exclusive access to it and can reliably
predict how long my jobs are going to take.

Please advise me if there are any incompatibilities/better
combinations/more efficient components, etc. I will be running them 99%
in Linux. My source is Ebuyer.co.uk

Sempron 2800 1.6GHz 256kb L2 cache AM2 940 pin (£37.65)

Asustek M2V AM2 VIAK8T890 Sound, Gigalan And USB 2.0 2000MHz FSB SATA
ATX (£40.59)

Ebuyer 512MB DDR2 533MHz PC2-4200 240pin Extra Value Ram (£19.88)

Seagate ST3250624A Barracuda 250GB 7200RPM ATA/100 16MB (£51.15)

Casecom KL-188 Silver ATX Midi Tower Case With 350W PSU (£12.76)

Extra Value Black Wired Multimedia keyboad - USB/PS2 (£2.49)

Relisys 'Weekend Special' TL535 15" 0.264dpi (1024x768) 8ms Multimedia
Ivory TFT Monitor with 3year On site warranty (£63.99)

Gecube R9200SE 128MB PCI 200MHz TV DVI - Passive heatsink totally
silent (£21.23)


Some questions:
(1) Will a PCI graphics card work with a PCIe mobo? As the computer
will be used at most for Word Processing and the rest for computations
with the monitor off, I didn't see the point in getting a souped up
graphics card. A nice silent, passive card suited me fine.

(2) Is DDR2-800MHz RAM worth it? It is hard to find and very expensive.
Most of the calculations involve simple but repetitive matrix
arithmetic (finite elements)

(3) Does the above Sempron come with its own heat sink? (quickfind
code: 111296)

(4) How overclockable is the AM2 Sempron 2800, and will I need a better
heat sink?

TIA.
 
Hi guys. I'll be buying a few of these PCs for number crunching with a
tight personal budget. My university has a parallel cluster but it is
saturated with jobs at the moment. At least having my own parallel
cluster would mean I have exclusive access to it and can reliably
predict how long my jobs are going to take.

Please advise me if there are any incompatibilities/better
combinations/more efficient components, etc. I will be running them 99%
in Linux. My source is Ebuyer.co.uk

Sempron 2800 1.6GHz 256kb L2 cache AM2 940 pin (=A337.65)

Asustek M2V AM2 VIAK8T890 Sound, Gigalan And USB 2.0 2000MHz FSB SATA
ATX (=A340.59)

Ebuyer 512MB DDR2 533MHz PC2-4200 240pin Extra Value Ram (=A319.88)

Seagate ST3250624A Barracuda 250GB 7200RPM ATA/100 16MB (=A351.15)

Casecom KL-188 Silver ATX Midi Tower Case With 350W PSU (=A312.76)

Extra Value Black Wired Multimedia keyboad - USB/PS2 (=A32.49)

Relisys 'Weekend Special' TL535 15" 0.264dpi (1024x768) 8ms Multimedia
Ivory TFT Monitor with 3year On site warranty (=A363.99)

Gecube R9200SE 128MB PCI 200MHz TV DVI - Passive heatsink totally
silent (=A321.23)


Some questions:
(1) Will a PCI graphics card work with a PCIe mobo? As the computer
will be used at most for Word Processing and the rest for computations
with the monitor off, I didn't see the point in getting a souped up
graphics card. A nice silent, passive card suited me fine.

(2) Is DDR2-800MHz RAM worth it? It is hard to find and very expensive.
Most of the calculations involve simple but repetitive matrix
arithmetic (finite elements)

(3) Does the above Sempron come with its own heat sink? (quickfind
code: 111296)

(4) How overclockable is the AM2 Sempron 2800, and will I need a better
heat sink?=20

TIA.
Click to expand...

Your first step is:

Determine whether Intel or AMD is the right platform for your problem.
I tried to help a guy a while back - had him convinced AMD was the
right answer for his problem, and the result was a big mistake. It
turns out for the memory access pattern his problem set had, that the
an Intel box would have had a higher rating. What I learned from
that exercise, is: find some sample computers and benchmark
the problem first. It could turn out, in your economic analysis,
that if one family is 50% more effective as another, then the
processor is worth more to you.

The next thing to note, is AMD is headed in the wrong direction when
it comes to AM2. The $65 USD Sempron for AM2 has _128KB_ cache for L2.
The $65 USD Sempron for S939 has 256KB cache for L2. Personally,
I would not buy a processor with less than 512KB cache. I don't
know exactly how a processor with a 128KB cache would behave, but
I presume you'd want to have a high performance main memory (L3)
to help a crippled design like that.

The Sempron performance number is compared to a Celeron, and not
a P4. The performance number of an Athlon64 is compared to a P4.
Thus, your Sempron 2800 is probably closer to a P4 2.4GHz. An
Athlon64 S939 3000+ has a 512KB L2, and costs $93 USD, and is
comparable to a P4 3.0GHz.

On the Intel side, the cheapest processor is Pentium D 805. It
is a dual core 2.66GHz/FSB533,2x1MB L2 processor. It is $113 USD.
While these have been overclocked (and that is the main reason
people have been buying them), they tend to run hot, and I would
not push them too far (excessive Vcore power consumption can make
the Vcore parts run hot).

In terms of motherboards, I would try to find a motherboard that
has build-in (Northbridge) graphics. That will save you the
price of a video card.

In terms of RAM, a guy was asking about latency not too long ago,
and in order to match latency with DDR2, requires expensive memory
to surpass DDR400 CAS2 memory. Whether you should even worry about
memory type, really depends on your problem type. If you are
compute bound, and memory is not an issue, then the cheapest
memory that will run error free, is what you want to find. But
if your problem type has a random memory access pattern, and
you are memory bound (like say some kind of simulation environment),
chances are the first cycle latency of the memory, would have a
significant bearing on your compute platform.

If your platform is dual channel, then you'll want to split
the RAM in half and buy two sticks. If you wanted a total of
1GB, then buy 2x512MB sticks and run them in dual channel.
The only platform where that wouldn't be true, is if you
ended up selecting an S754 Athlon platform, as that uses
single channel memory. (You would use a single 1GB stick
in that case.)

Here is an example of a motherboard that has an LGA775
socket, and can run a 805 dual core. This board has an AGP
slot, but also has built-in VGA graphics, and uses DDR memory.
$56 USD. There are some other brands, that use the 865GE
chipset, and have the LGA775 socket like this one does.
Since so many people try to overclock the 805, it is
a good idea to see whether the BIOS has a good overclocking
feature set, before you buy.

Gigabyte GA-8I865GME-775 (LGA 775) Intel 865G Micro ATX - Retail $56 USD
http://www.newegg.com/Product/CustRatingReview.asp?Item=N82E16813128008

Now to your questions:

(1) Will a PCI graphics card work with a PCIe mobo...

Yes. Set the Primary graphics adapter to PCI and it should work fine.
Or if a motherboard has built-in graphics, use the default settings.

(2) Is DDR2-800MHz RAM worth it? It is hard to find and very expensive.
Most of the calculations involve simple but repetitive matrix
arithmetic (finite elements)

On AM2, most motherboards seem to have immature BIOS, and there is
a fair bit of trouble getting RAM that is compatible. While I might
considering tinkering with DDR2-800 memory on an Intel platform,
on AM2 right now, getting _anything_ that works is more important.
Hell, I might even spring for ECC memory, considering the state
of the platform.

(3) Does the above Sempron come with its own heat sink? (quickfind
code: 111296)

On this Manila AM2 with 128KB L2, the answer is Yes.
http://www.newegg.com/Product/Product.asp?Item=N82E16819104301

(4) How overclockable is the AM2 Sempron 2800, and will I need a better
heat sink?

You are on a budget. Of course, you are going to try to overclock
with the stock heatsink, and there is every possibility you will
be happy without spending extra cash on exotic cooling. Since
every processor is different, overclocking comes with no guarantees.
But I don't see a reason you could not aim for a 50% overclock on
the 2800. The tech should have the headroom. It all depends on
how severely these things are binned.

Paul
 
So did you find any benchmarks on that processor? You have to find a way to
compare it to other processors.

I would question the power of these compared to say a single core 3400 AMD
64.


Hi guys. I'll be buying a few of these PCs for number crunching with a
tight personal budget. My university has a parallel cluster but it is
saturated with jobs at the moment. At least having my own parallel
cluster would mean I have exclusive access to it and can reliably
predict how long my jobs are going to take.

Please advise me if there are any incompatibilities/better
combinations/more efficient components, etc. I will be running them 99%
in Linux. My source is Ebuyer.co.uk

Sempron 2800 1.6GHz 256kb L2 cache AM2 940 pin (£37.65)

Asustek M2V AM2 VIAK8T890 Sound, Gigalan And USB 2.0 2000MHz FSB SATA
ATX (£40.59)

Ebuyer 512MB DDR2 533MHz PC2-4200 240pin Extra Value Ram (£19.88)

Seagate ST3250624A Barracuda 250GB 7200RPM ATA/100 16MB (£51.15)

Casecom KL-188 Silver ATX Midi Tower Case With 350W PSU (£12.76)

Extra Value Black Wired Multimedia keyboad - USB/PS2 (£2.49)

Relisys 'Weekend Special' TL535 15" 0.264dpi (1024x768) 8ms Multimedia
Ivory TFT Monitor with 3year On site warranty (£63.99)

Gecube R9200SE 128MB PCI 200MHz TV DVI - Passive heatsink totally
silent (£21.23)


Some questions:
(1) Will a PCI graphics card work with a PCIe mobo? As the computer
will be used at most for Word Processing and the rest for computations
with the monitor off, I didn't see the point in getting a souped up
graphics card. A nice silent, passive card suited me fine.

(2) Is DDR2-800MHz RAM worth it? It is hard to find and very expensive.
Most of the calculations involve simple but repetitive matrix
arithmetic (finite elements)

(3) Does the above Sempron come with its own heat sink? (quickfind
code: 111296)

(4) How overclockable is the AM2 Sempron 2800, and will I need a better
heat sink?

TIA.
 
Last said:
So did you find any benchmarks on that processor? You have to find a wayto
compare it to other processors.

I would question the power of these compared to say a single core 3400 AMD
64.


Hi guys. I'll be buying a few of these PCs for number crunching with a
tight personal budget. My university has a parallel cluster but it is
saturated with jobs at the moment. At least having my own parallel
cluster would mean I have exclusive access to it and can reliably
predict how long my jobs are going to take.

Please advise me if there are any incompatibilities/better
combinations/more efficient components, etc. I will be running them 99%
in Linux. My source is Ebuyer.co.uk

Sempron 2800 1.6GHz 256kb L2 cache AM2 940 pin (£37.65)

Asustek M2V AM2 VIAK8T890 Sound, Gigalan And USB 2.0 2000MHz FSB SATA
ATX (£40.59)

Ebuyer 512MB DDR2 533MHz PC2-4200 240pin Extra Value Ram (£19.88)

Seagate ST3250624A Barracuda 250GB 7200RPM ATA/100 16MB (£51.15)

Casecom KL-188 Silver ATX Midi Tower Case With 350W PSU (£12.76)

Extra Value Black Wired Multimedia keyboad - USB/PS2 (£2.49)

Relisys 'Weekend Special' TL535 15" 0.264dpi (1024x768) 8ms Multimedia
Ivory TFT Monitor with 3year On site warranty (£63.99)

Gecube R9200SE 128MB PCI 200MHz TV DVI - Passive heatsink totally
silent (£21.23)


Some questions:
(1) Will a PCI graphics card work with a PCIe mobo?
Click to expand...

SURE, just not in the PCIE slot. (I think) You should be able to use
any free standard PCI solt.


As the computer
will be used at most for Word Processing and the rest for computations
with the monitor off, I didn't see the point in getting a souped up
graphics card. A nice silent, passive card suited me fine.

(2) Is DDR2-800MHz RAM worth it? It is hard to find and very expensive.
Most of the calculations involve simple but repetitive matrix
arithmetic (finite elements)

(3) Does the above Sempron come with its own heat sink? (quickfind
code: 111296)

(4) How overclockable is the AM2 Sempron 2800, and will I need a better
heat sink?
Click to expand...

It would be best to err on the side of caution, and say, YES. If you
must overclock, you should have a better 'sink.
 
Paul said:
Your first step is:

Determine whether Intel or AMD is the right platform for your problem.
Click to expand...

http://www.amd.com/us-en/Processors/SellAMDProducts/0,,30_177_863_8800~78418,00.html

(link may need to be concatenated)

It would seem AMD is better.

Of course I am hoping whatever performance gains that resulted in the
Opteron beating the Itanium 2 and Xeon would be transferable to a
Sempron.

The thing about the Opteron is that I could probably afford one dual
core Opteron for 2-3 Sempron systems, so I think it may be better to
get a few Semprons.


The next thing to note, is AMD is headed in the wrong direction when
it comes to AM2. The $65 USD Sempron for AM2 has _128KB_ cache for L2.
The $65 USD Sempron for S939 has 256KB cache for L2. Personally,
I would not buy a processor with less than 512KB cache. I don't
know exactly how a processor with a 128KB cache would behave, but
I presume you'd want to have a high performance main memory (L3)
to help a crippled design like that.
Click to expand...

Yeah, I was surprised that according to Tom's Hardware Guide, the AM2
processors were mostly on par with S939 or 940 pin CPUs, even with
their faster DDR2 memory.

However the AM2 Sempron 2800+ was the cheapest 64 bit, non-Socket A
Sempron I could find.
The Sempron performance number is compared to a Celeron, and not
a P4. The performance number of an Athlon64 is compared to a P4.
Thus, your Sempron 2800 is probably closer to a P4 2.4GHz. An
Athlon64 S939 3000+ has a 512KB L2, and costs $93 USD, and is
comparable to a P4 3.0GHz.
Click to expand...

Thanks! Didn't know that...

In terms of RAM, a guy was asking about latency not too long ago,
and in order to match latency with DDR2, requires expensive memory
to surpass DDR400 CAS2 memory. Whether you should even worry about
memory type, really depends on your problem type. If you are
compute bound, and memory is not an issue, then the cheapest
memory that will run error free, is what you want to find. But
if your problem type has a random memory access pattern, and
you are memory bound (like say some kind of simulation environment),
chances are the first cycle latency of the memory, would have a
significant bearing on your compute platform.
Click to expand...

Hmm, hard to tell. Some of my runs use something like 99% CPU and 10%
RAM (about 100MB). Others use 800MB of RAM, especially if I use double
precision calculations.

(2) Is DDR2-800MHz RAM worth it? It is hard to find and very expensive.
Most of the calculations involve simple but repetitive matrix
arithmetic (finite elements)

On AM2, most motherboards seem to have immature BIOS, and there is
a fair bit of trouble getting RAM that is compatible. While I might
considering tinkering with DDR2-800 memory on an Intel platform,
on AM2 right now, getting _anything_ that works is more important.
Hell, I might even spring for ECC memory, considering the state
of the platform.
Click to expand...

Thanks about the heads up on the AM2 platform. I will consider a S939
or S940 instead.

Thanks for your informative post again.
 
Hi guys. I'll be buying a few of these PCs for number crunching with a
tight personal budget. My university has a parallel cluster but it is
saturated with jobs at the moment. At least having my own parallel
cluster would mean I have exclusive access to it and can reliably
predict how long my jobs are going to take.

Please advise me if there are any incompatibilities/better
combinations/more efficient components, etc. I will be running them 99%
in Linux. My source is Ebuyer.co.uk

Sempron 2800 1.6GHz 256kb L2 cache AM2 940 pin (£37.65)

Asustek M2V AM2 VIAK8T890 Sound, Gigalan And USB 2.0 2000MHz FSB SATA
ATX (£40.59)
Click to expand...
Ebuyer 512MB DDR2 533MHz PC2-4200 240pin Extra Value Ram (£19.88)
Click to expand...

Number crunching? And you're going with cheap generic
memory? I hope your results won't be important.
Consider advanced ECC Chipkill memory, or, at a minimum,
plain vanilla ECC.

-- Bob Day
http://bobday.vze.com
 
Bob said:
Number crunching? And you're going with cheap generic
memory? I hope your results won't be important.
Consider advanced ECC Chipkill memory, or, at a minimum,
plain vanilla ECC.
Click to expand...

Thanks Bob. Yeah, I was a bit iffy about that and was wondering if
anyone would comment on it :-/

The thing is that I've read the reviews on the memory and most people
say it is OK and they got no problems. IIRC it got 5/5 stars.

Of course as I plan on overclocking, the memory and CPU would
effectively be tested together with a Prime95 torture test before the
simulations start. I could also test the memory independently if there
are problems.
 
Bob Day wrote:
Click to expand...
Number crunching? And you're going with cheap generic
memory? I hope your results won't be important.
Consider advanced ECC Chipkill memory, or, at a minimum,
plain vanilla ECC.
Click to expand...

Incidentally, I thought I'd mention that the nature of the computations
isn't one mega-long run where errors accrue (in which case 100%
accuracy is critical), but rather many moderate-cost runs where the
rare numerical error's effect is compartmentalised to messing up one
run.

In this case, not worth ECC RAM, IMVHO. AIUI non-ECC RAM rarely messes
up anyway. I have non-ECC Crucial RAM on one machine and have run the
Prime95 torture test & memtest overnight -- no errors.
 
Hmm, hard to tell. Some of my runs use something like 99% CPU and 10%
RAM (about 100MB). Others use 800MB of RAM, especially if I use double
precision calculations.
Click to expand...


That's a pretty important piece of information! Maybe you should skip the
graphics cards, and get boards with on-board video and stick the savings
into better, more, and more reliable RAM. Just a thought.

~e.
 
Incidentally, I thought I'd mention that the nature of the computations
isn't one mega-long run where errors accrue (in which case 100%
accuracy is critical), but rather many moderate-cost runs where the
rare numerical error's effect is compartmentalised to messing up one
run.

In this case, not worth ECC RAM, IMVHO. AIUI non-ECC RAM rarely messes
up anyway. I have non-ECC Crucial RAM on one machine and have run the
Prime95 torture test & memtest overnight -- no errors.
Click to expand...

It would be good to run the latest memtest86+ for at least
24 hours. Even so, having had no problems on another system
is obviously no assurance of same result on a different
system, different memory, and overclocked at that.

Two other things;
Find some benchmarks of your code running that compare
results from same CPU architecture but different L2 cache
sizes. "Sometimes" the L2 cache size makes a large
difference and if so, you might want to go with more L2 than
a Sempron has.

Also investigate the memory throughput on that Via chipset
vs nVidia alternatives. I don't know how it does, but that
too can be significant.
 
Incidentally, I thought I'd mention that the nature of the computations
isn't one mega-long run where errors accrue (in which case 100%
accuracy is critical), but rather many moderate-cost runs where the
rare numerical error's effect is compartmentalised to messing up one
run.

In this case, not worth ECC RAM, IMVHO. AIUI non-ECC RAM rarely messes
up anyway. I have non-ECC Crucial RAM on one machine and have run the
Prime95 torture test & memtest overnight -- no errors.
Click to expand...

No errors in 24 hrs does not mean no errors over the life of the
machine. Also clocked machines have a habit of creep of their
characteristics, meaning an initially stable machine can end up
erroring more and more as time goes by.

Do you want to have results that are wrong here and there, but you dont
know which results are wrong? I dont know what work youre doing
exactly, but on the face of it this doesnt sound like a good scenario.

Clocking increases odds of errors greatly, and is suited to situations
where the occasional error is no big deal, which sounds about the
opposite of what youre doing.

I know nothing about this point, but will mention I've vaguely heard of
linux badram, which enables reliable computing on machines making
hardware errors.

Do you need 250G hdd space per machine? If not you could get used
drives and sink the money saved into more machines. 20G drives are much
cheaper.

Why would you buy a bunch of 15" monitors when you can get used ones
for free? Since youre doing number crunching, not fancy pretties, it
shouldnt matter a dried turd what kind of monitor you use. I've no idea
if you could run some of the machines monitorless, but used monitors
are so cheap you might as well get a pile.

Same again with graphics cards, a bunch of PCI cards off scrap machines
will do fine IIUC.

If your goal is most crunch per dollar, cutting out all those pointless
costs will give you more processing power for your bucks.

I assume you know what this octopus will cost to run, and have factored
this into your budget.


NT
 
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