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CPU config conundrum:dual core opteron/athlon

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August 4, 2005 10:53:39 AM

Hi,

I need to buy a new computer for my work, and I need to decide on a CPU config. Any help/advice, pointing in the right direction would be much appreciated. I will use the PC essentially for very intense number-crunching/computation. As of now, I use the machine for large scale string matching/comparision (genome comparisions). I have run the scripts on a dual Itanium (IA64) 1.8 GhZ processor with 4 Gb RAM and on an AMD Athlon64 3000+ with 1 Gb of RAM. Depending on the scripts (whether the script needs to open a large number of files, as opposed to doing plain string matching), either the AMD is faster, or the dual processor, because of more memory, is faster.
I now want to buy a new machine for similar sort of work. What I am curently considering is an AMD AthlonX2 3800+ on a dual processor board dual core-dual processor (i.e. 4 processors in all), with 4 Gb memory.The other alternative is a dual processor dual core opteron. However, it has been my experience that server class processors are much slower than desktop processors (eg. the dual itanium v/s the AMD 64 athlon).I have also read that server class processors are different in terms of performance compared to desktop class. Is this true ? Am I better off going for a dual Athlon, as opposed to a dual opteron ?

I am not considering intel since
a) Reviews suggest that Intel is faster only in multi-media applications,and I will not be doing any multimedia work.
b) AMD has worked well for me this far

Should Intel be included in the list of contenders ?
Could you also please suggest what motherboards I ought to consider ?
Thanks in advance.

Cheers,
Metalcup
August 4, 2005 11:18:54 AM

You can't use Desktop A64 chips in server boards.

You'll either have to use just a single dual-core A64, or build a 2-way opteron system.

Same as Intel's Xeons and P4s.

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<font color=red>"Life is <i>not</i> like a box of chocolates. It's more like a jar of jalapeńos - what you do today might burn your a<b></b>ss tommorrow."
August 4, 2005 12:59:08 PM

Thanks ChipDeath..,

I know I cannot use desktop A64 chips on server boards, and vice-versa. What I wanted to know is if I could install dual core Athlon CPU's on a dual processor desktop motherboard. Do such boards exist ?
If that is not possible, would a dual core, dual processor Opteron be faster/more efficient for the stuff I am doing than a single dual core AMD64 ?
Any pointers on where I can read up more will be very useful. I have read stuff from THG, Anandtech, Sharkyextreme, but couldn't find any answers.

Thanks
Related resources
August 4, 2005 1:46:17 PM

What I meant was there are no dual socket boards for 'Normal' A64 chips, so if you must have more than 2 CPUs You'll have to go with an Opteron rig.

Of course the Athlon X2 (dual core) chips will work in Virtually all the newer Socket 939 boards (some might need a BIOS update, but that's no biggie), so if 2 cores will do, you could still go with the X2.

In theory there should be very little performance difference between a 2 single-core Opteron and a single Dual-core A64, assuming they're running at the same clockspeed. Most of the difference will be through the motherboard and/or memory setups than anything (As the opteron boards are going to be geared for stability, whereas A64 boards will tend to run things a little more agressively).

Plus of course you'll have much more in the way of overclocking options on the A64 boards, if that floats your boat. Not that I'd recommend Overclocking for 'critical' hardware anyway of course... But I don't know how important your work is.

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<font color=red>"Life is <i>not</i> like a box of chocolates. It's more like a jar of jalapeńos - what you do today might burn your a<b></b>ss tommorrow."
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August 4, 2005 2:18:29 PM

You didnt mentionned ECC ram, wich is probably a good thing for project like his. Usually scientific programs are less fault tolerant, and with 4 gb of ram ECC is probably the way to go anyhow

Asus P4P800DX, P4C 2.6ghz@3.25ghz, 2X512 OCZ PC4000 3-4-4-8, MSI 6800Ultra stock, 2X30gig Raid0
August 4, 2005 2:33:47 PM

Ah yes, very true. I guess it all depends on budget and just how critical the task is.
Quote:
Usually scientific programs are less fault tolerant

While this is undoubtedly true, I'm a bit wary of coming across as suggesting the A64 system will cock up and give crap results - it won't really... Just think how many people are running Folding@home on A64 rigs, and what he's wanting to do sounds reasonably similar.

That said though, none (or few at least) of those A64 systems are running 4Gb of RAM.....

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<font color=red>"Life is <i>not</i> like a box of chocolates. It's more like a jar of jalapeńos - what you do today might burn your a<b></b>ss tommorrow."
August 4, 2005 2:58:10 PM

>I have run the scripts on a dual Itanium (IA64) 1.8 GhZ
>processor

Someone should intel they have 1.8 GHz itania now, they are not yet aware of that themselves :) 

>Depending on the scripts (whether the script needs to open
>a large number of files, as opposed to doing plain string
>matching),

strings means integer workloads, means Itanium is usually a poor match. Just out of curiousity, what language and what compiler (or VM) did you use ?

>What I am curently considering is an AMD AthlonX2 3800+ on
>a dual processor board dual core-dual processor (i.e. 4
>processors in all)

No go. A64s are strictly single socket, desktop solution. If you want more than one socket, youll need opterons, which are also available in dual core.

>However, it has been my experience that server class
>processors are much slower than desktop processors

Server processor are qualified differently from desktop parts, and favor stability and reliability over absolute speed, so typically they run at lower clockspeed/fsb/ram timings (while costing more).

That said, opteron has the exact same core as A64s (with 1mb cache), so performance will be about the same per clock, with only one minor caveat: opterons require registered RAM, which is a tad slowed than unregistered RAM. But if you are looking at that much RAM, registered (maybe even in combination with ECC) is the way to go anyway.

>a) Reviews suggest that Intel is faster only in multi-media
> applications,and I will not be doing any multimedia work.

The only way to know for certain, is to test. Be adviced that the performance potential of home brew software is likely in the order of a factor 2x-10x, unless you have very skilled developpers and/or have spent a large time optimizing the code, so dont be too quick blame/rave a certain cpu.

>Should Intel be included in the list of contenders ?

Never hurts to test it on a desktop P4, that will give you a good idea how it will perform on Xeons. But if you really need 4 cores, opteron will be leaps and bounds cheaper, as you can use cheapo 2 socket boards. For you workload I would safely ignore Itanium though.

>Could you also please suggest what motherboards I ought to
>consider ?

Do you want to build a machine, or buy one from an oem ? If buying, check out HP or Sun for dual/dual opterons. If you want to save a pretty penny (but lose decent support!), by building one yourselve, Id recommed a dual core ready Tyan board with 8 Dimm slots for upgradeability, such as this one:
<A HREF="http://www.newegg.com/Product/Product.asp?Item=N82E1681..." target="_new">http://www.newegg.com/Product/Product.asp?Item=N82E1681...;/A>


= The views stated herein are my personal views, and not necessarily the views of my wife. =
August 4, 2005 10:29:40 PM

I agree with P4man, if you can test it out on a fast P4 to see how it performs then that could tell you more about ruling out Intel or not. Still a two dual processor Opeteron derivative system seems to be a rather strong number cruching configuration with the much lower latency memory controller design of AMD it would be hard for me to believe Intel would be better for what you describe. Still if you can test first then that would probably settle it for you.
August 5, 2005 6:48:13 AM

Thanks for all the replies.

The Itanium is a 1.6 GhZ machine, sorry :) 

I use perl, C and fortran for work, using the GNU C compiler package, and perl ver. 5.8.3,; all of them compiled/installed for 64 bit AMD.

My code is not 'optimised', so that is a drawback.
I will most likely go for building the machine, depending on the price difference.

I am not as concerned about stability as I am about raw crunching ability. I have non ECC, DDR-RAM on the AMD athlon 64 machine I use currently, and I don't think it has crashed more than once or twice in the last year, inspite of the heavy workload, and I can live with that frequency of crashes.

I don't think I want to overclock the machine though - that might be a bit risky.

Ok, one last question..
A dual processor, dual core (i.e. 4 processors) Opteron 64 would be much faster than a single processor dual core AMDX2 athlon right , assuming ofcourse, that the clock speeds are in the same range..

I am hunting for an Intel system to test..let's see..

Thanks
cheers,
Metalcup


<P ID="edit"><FONT SIZE=-1><EM>Edited by metalcup on 08/05/05 02:52 AM.</EM></FONT></P>
August 5, 2005 8:09:02 AM

>and I can live with that frequency of crashes.

ok, but also consider if you can live with potentially wrong results non ECC RAM might produce like twice a year and go by unnoticed. Since ECC Ram isnt that much more expensive, and for opteron you need registered ram anyway, Id still recommend it.

>A dual processor, dual core (i.e. 4 processors) Opteron 64
>would be much faster than a single processor dual core
>AMDX2 athlon right

Well, only if your software is properly multithreaded and is capable of running 4 independant threads. Or if you can run several simultaneous instances of your application, but in that case, simply using 2 desktop X2s might be a lot cheaper than a 2x2way opteron. If your code only spawns a single cpu bound thread, 4 core opteron will be slower than an X2 4800+ which will be slower than a single core A64 FX57...

= The views stated herein are my personal views, and not necessarily the views of my wife. =
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