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What's the difference between a server CPU and a desktop CPU?

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DreamerBrian

Member
Joined
Sep 19, 2010
Location
Seattle
So I decided to turn my old rig into a Smoothwall/IPCop server. I did a little digging, and since this would be my first server build I found out that there is a difference between a desktop CPU and a server CPU (only by the different genre of CPU when I started looking through Newegg). There's Intel Xeons and AMD Opterons... two processors I haven't any experience with (nor have I heard of). I'm assuming that if there's a whole different model then there has to be a significant difference between a desktop CPU and a server CPU. I could have Google'd a couple of random sites but I decided to get the first impression from the resident experts :salute:.

Who's got the answer?

Brian
 
1. Registered Ram ECC / buffered /unbuffered
2. Different chipsets usually allowing more ram and other things like Raid and such
3. Sometimes a different socket then their desktop parts
4. Ability to use multiple CPU's in one motherboard, example you cant put multiple i7 processors in a motherboard, but you can get multi socket 1366 Xeon motherboards.
 
Typicaly server cpu's on the hole have superior i/o throughput. If they are of a multi-Processor series of the chip they an increased amount of input output lanes, so that they can communicate at full capacity with other processors. Biggest thing you will notice is l1 l2 l3 cache are usually much larger which helps with this.

The thing to ask yourself first in this case is what your trying to do. If your not trying to do anything super aggressive you don't need to push into the higher features. Once you go into the larger options the chip and mother board prices start to go up in price fast.

Give me a better idea of what your trying to do either in this thread or send me a message and can head you in the right direction. Its kinda difficult to really summarize the chips and how they might perform for you without some idea of how you want to use them.
 
I'm going to be putting Smoothwall/IPCop on it so initially I'm only going to be screwing around with the firewall capabilities, but eventually I'll most likely get into FTP, Proxy, DNS, HTTP, etc etc. Prettymuch whatever the rig's hardware lets me do.
 
Unless you have a very specific server application requiring the use of a server CPU, a regular desktop will do everything just as well. Server CPUs are mainly designed for cluster computing, but usually use the same technology as the desktop equivalent. So with a single CPU you would be hard pressed to tell the difference.
 
I'm going to be putting Smoothwall/IPCop on it so initially I'm only going to be screwing around with the firewall capabilities, but eventually I'll most likely get into FTP, Proxy, DNS, HTTP, etc etc. Prettymuch whatever the rig's hardware lets me do.

Well you certainly don't need much in the form for cpu. If your building this mostly as a testbed for experimenting with software then you might want to look for a barebones server bundle. Single processor systems usually the cheapest and you tend to find the majority of those as xeon systems. If you watch newegg well you can sometimes score a xeon system with the cpu thrown int the bundle for around 500$, all you need to add is memory and a hard drive. and your set.

Another note if this is mainly gonna be a test bed and you want to invest in a server class cpu. Check out VmWares ESXi server. Base version is free. Its a server hypervisor, it installs with ease on compatible hardware. It allows you to run a number of installs and then access them inside the VMware vSphere client, which means you can put the server anywhere (perferrably somehwere quiet) and you only really need to plug it into the network and have it set the the correct network, and then all the visual and inputs for desktop control are handle through the vSphere client. Super big time saver, allows you to make great use of the cpu cycles and ram you have in the box, aswell as storage. Beats building a new box everytime you want to test an os install and stuff like that.

ooh quick break down of processors.
Xeon 3000 series single processor systems, fits in some i7 boards aswell. Dependsing on series number
Xeon 5000 series - these are dual processor capable processors, for systems with two physical cpu's
Xeon 7000 series - quad+ capable processors, for systems with 4- 16max(i think 16 is the max not 100% sure) physical cpu systems. Most expensive xeon, the boards cost a ton aswell. (1k-4k pricetag for some of these chips)

Opteron 4000 series, single to dual physical processor systems.

Opteron 6000 series, dual to quad physical processor systems.

In most cases the max ram for a single processor system is currently 24-32gb of ram with 64gb being the limit most probably by the end of the year on the newer xeon cores.

Dual processor systems are currently capable of up to 96-128gb of ram. This is where the extra IO channels for the larger server chips start to come in handy. As the physical cpu's go up the ability to handle more memory goes up aswell.

Quad processor systems are capable of 512gb to 1tb of ram depending on the motherboard.

If this isn't enough information to help you let me know.
 
Wow thanks for the detail, Juan. I just built this rig in September and she still only red lines when I convert multiple videos at a time so I think i'll look into the VMWare server applications.

I found out today that I need to buy a WAN NIC for this rig if I want to run a software-based firewall :/
 
Unless you have a very specific server application requiring the use of a server CPU, a regular desktop will do everything just as well. Server CPUs are mainly designed for cluster computing, but usually use the same technology as the desktop equivalent. So with a single CPU you would be hard pressed to tell the difference.

they aren't mainly made for cluster computing, they are made just to handle more work load, use ECC ram so you dont get errors and so on.
 
they aren't mainly made for cluster computing, they are made just to handle more work load, use ECC ram so you dont get errors and so on.

Biggest thing in server cpu's is increased i/o, Superior Double precison and single precision floating point calculation, and less overall internal data transit time between cores, and cache points. In chips like the 7500 xeons they have the same predictive branching as the itanium chips which i think means but not 100% sure so don't quote me allows them to complete 3/6 threads per core aswell.

HyperThreading is a great example of something that was the effect of the original race to the 64bit platform for desktops. However depending on the architecture and what you are doing there can be a performance hit from it. If your doing double precision floating point calculations chances are you will take a performance hit if you try to run 8 threads on 4 cores. However if your running single precision floating point you usually see a vast improvement in performance.

New opteron chips are also capable of running 2 threads per core. They look to perform similarly to the xeons for double precision floating point calculations when running two threads per core aswell. Atleast on paper.

The big trick for larger higher performance servers is to calculate out how many MHZ each user request requires. Or in the case of parallel computation, you figure out how much time each work packet on average will take to compute. From there you can figure out what you need from a server. Some applications like databases are extremely memory intensive, and depending on the size can be cpu intensive aswell. Storage servers that perform san functions tend to use alot of CPU aswell as ram, and also need a large amount of performance to the PCI bus, so handle large volumes of drives. Web services servers deal largely on a CPU basis and how well the software is written. Performance on custom software varies alot. However you can generally figure out if more mhz, or mabye more processors will benifit it.

I can literally go on for hours on this stuff. Happens to be a large part of what I do for a living these days.

As for as needing additional network cards, when you virtualize the system or most medium/enterprise routers, you can split the interfaces to act as multiples cards. Since your not pushing for throughput at this point, one gigabit connection is gonna be more than enough to support the entire server. You can allways add more network cards later and assign them to be directly mapped to a Virtual machine aswell. However in this cause i think you will be happy with the 1-2 ports that are fairly standard on most barebones servers these days.
 
Awesome. The CPU i'm going to buy (3.2GB single core P4) is 14 dollars nowadays. How great is that!
 
Awesome. The CPU i'm going to buy (3.2GB single core P4) is 14 dollars nowadays. How great is that!

If your planning to use VMware ESXi you will need a processor that that has the virtualization instruction set which mostly cpu's made in the last 3-4 years, and are not value cpu's, Celerons don't have support for that instruction set, Some atom cpu's have support of it, but they mostly aren't capable of 64bit code.
 
yes the i5's have the instruction set required for it. Most newer cpu's do since large amounts of software are starting to use virutalization as a data protection method.
 
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