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I was getting specs for dell server and one cpu is an Intel Xeon with 6 cores, another 4 cores. What am I getting with this? Do I need six cores? What does that give me? I don't know what mult-core cpus give me but that's about all I can get.

thanks for any help.

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closed as not a real question by SvW, Tom O'Connor, MDMarra, Ward, ewwhite Dec 2 '11 at 17:49

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

    
why would someone vote to close this? –  johnny Dec 2 '11 at 17:11
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Because your question is akin to asking why anyone would need a container ship when there are row boats available. –  SvW Dec 2 '11 at 17:18
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If you're shopping for servers and you don't know what the benefits of multiple cores are, you shouldn't be the one shopping for servers. –  MDMarra Dec 2 '11 at 17:26
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Sorry to not be in the club. I will refrain from asking basic questions so as not to bother the elite. I had a genuine question about what a multi-core cpu is for, not what server to buy. Mascarpone has the best solution, better question wording. –  johnny Dec 2 '11 at 17:31
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@johnny This is a site for professional systems administrators, per the faq. Asking how multiple cores work is a fundamental computing questions, and as such, is not a good fit for this site. –  MDMarra Dec 2 '11 at 17:32

3 Answers 3

up vote 5 down vote accepted

You can consider a 6 core CPU as six independent CPUs, which will have up to 6 times the computing power than a single CPU.

What you really get out of it is highly dependent of what you want to do with this server. Some workloads don't benefit at all from multicore systems, others really need them to perform acceptable. All in all, a general file/web/mail server will nearly always benefit from more CPUs, but to a varying degree.

In short: It depends.

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I thought you had to have software that took advantage of the other cores. Does Windows automatically use the multi-cores or is this a function of how the motherboard processes data? It splits it up or runs concurrent... –  johnny Dec 2 '11 at 17:18
    
If you have a single core, all task running in a given system will have to compete for computing time, when you have more cores, you will have more time to share. But yes, software will need to take multiprocessing into account to really benefit from it, but most server software does this, unless it's specific purpose will make it unfeasible. –  SvW Dec 2 '11 at 17:21
    
@johnny Windows automatically uses multi-cores and even multi processor systems depending on the windows version. For example windows server 2008 can handle more than 256 or 512 hardware threads if I'm not mistaken –  Ghita Dec 2 '11 at 17:22
    
@johnny Windows itself will use multiple cores just fine. Each application is different though. Some things, like Exchange, take well to multiple cores. Others, like Firebird backed applications, don't use them at all. –  sysadmin1138 Dec 2 '11 at 17:22
    
It has little to do with the motherboard or the operating system: Windows does nothing about it. Roughly speaking, the more cores you have, more processes (i.e. more running programs) you can have simultaneously without interfering with each other (ok, not exactly that, but something like that). –  lvella Dec 2 '11 at 17:27

A multiple core cpu is like having multiple cpu's on a single motherboard. What multi-core cpu's give you depend on what you are running... it's a matter of will you be running any software on the server that takes advantage of the multiple cores?

Where multi-core cpu's are immensely helpful is where you are running an application that is written to take advantage of them; that is, specifically, multi-threaded applications. Many (perhaps most) legacy apps were written for a single cpu model, so for these it makes little or no difference.

But an app written as a multi-threaded app will be able to take full advantage of those extra cores. As an example, we run an app that used to be single-threaded. It was modified by our programmers to be multi-threaded, and it now runs almost 20x faster on our dual xeon, 24 core dell (each xeon has six physical core, and each is "hyper-threaded", making for 12 logical cores.

Another potential area where multi-core cpu's could be immensely advantageous is where you are running virtual machines. I know that Vmware lets you assign one or more cores to each virtual machine; in these cases, the performance can increase linearly, depending on the application. If the app is i/o bound, multiple cores will still help, but not to the same extent as when it is cpu bound.

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Whilst i can't fully answer your question, you certainly can use the 'Set Affinity' per process or if you have rendering applications i.e. CAD 3D rendering or graphic modelling; it would certainly benefit from multiple core CPUs.

In a very general point of view, the more cores, the faster the application runs (of course the program must have been designed to handle multi-core processing).

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