[unh247]

Hello,

Myself and 2 other ME seniors are working on modeling an array of offshore wind turbines in OpenFOAM. We are building our own computer to run some simulations and experiment in OpenFOAM on. We pitched this computer to the department as a computer that could be used by future senior design groups to experiment on OpenFOAM and Ubuntu with. We budgeted $1000 for the computer, but we do have an additional $600 we can spend on the project. The following is what we have planned for the computer. We are planning on using a surplus monitor, mouse, and keyboard from our engineering building. Any suggestions or feedback would be greatly appreciated. Thanks!

Item PN QTY Price Description
1 N82E16819117369 1 $339.99 Intel i7-4790K Processor
2 N82E16813132215 1 $79.00 ASUS B85M-G Motherboard
3 N82E16820104445 2 $291.98 HyperX Ram DDR3 1600 (2x8gb)
4 N82E16817139010 1 $89.98 Corsair Power Supply 750W ATX
5 N82E16822236624 1 $132.00 Western Digital 2TB HD
6 N82E16827136276 1 $17.99 LG DVD Burner
7 N82E16833166005 1 $9.99 Ethernet Card
8 N82E16811139021 1 $109.99 Corsair Micro ATX Case
Total: $1070.93

[wyldckat]

Greetings unh247,

Let's see, here are a few questions and suggestions on each item:

• $339.99 Intel i7-4790K Processor
  • Are you planning on over-clocking this CPU?
• $79.00 ASUS B85M-G Motherboard
  • Seems OK.
• $291.98 HyperX Ram DDR3 1600 (2x8gb)
  • What "CL" value does it have? CL9, CL10 or CL11?
• $89.98 Corsair Power Supply 750W ATX
  • Only necessary if you need to put in a powerful graphics card and several hard-drives. Otherwise, you can reduce to something at the 600W mark.
• $132.00 Western Digital 2TB HD
  • Feels a bit overly expensive... in comparison to the CPU... is it a special edition hard-drive?
• $17.99 LG DVD Burner
  • No problem here.
• $9.99 Ethernet Card
  • Do you need a second network port? If not, this isn't needed...
  • ... although sometimes the network chip in the motherboards isn't supported properly on Linux... so perhaps this card might be useful.
• $109.99 Corsair Micro ATX Case
  • Feels a bit expensive... I think you can find something for half that price.

I think you're relying too much on the integrated GPU to manage to help you post-process properly the results. A $100-120 GPU card would likely serve you better.


Best regards,
Bruno

[unh247]

Hi Bruno,

Thanks for getting back to me so quick! To answer your questions:

$339.99 Intel i7-4790K Processor
Are you planning on over-clocking this CPU?
--Since my earlier post we got some advice from another student who has done some CFD work and he recommended a 325.99 Intel Xeon E3-1271 V3 3.6GHz Quad-Core Processor and I think we are going to go with that such that we don't have to worry about overclocking.

$79.00 ASUS B85M-G Motherboard
Seems OK.

$291.98 HyperX Ram DDR3 1600 (2x8gb)
What "CL" value does it have? CL9, CL10 or CL11?
--They have CAS Latency 10. Think it is worth it to shoot for 9?

$89.98 Corsair Power Supply 750W ATX
Only necessary if you need to put in a powerful graphics card and several hard-drives. Otherwise, you can reduce to something at the 600W mark.
--Valid point, see below about graphics card.

$132.00 Western Digital 2TB HD
Feels a bit overly expensive... in comparison to the CPU... is it a special edition hard-drive?
--More advice since posting was to get a SSD. We compromised and are planning on going with a "Hybrid" 1TB 120GB SS Cache WD HD

$17.99 LG DVD Burner
No problem here.

$9.99 Ethernet Card
Do you need a second network port? If not, this isn't needed...
... although sometimes the network chip in the motherboards isn't supported properly on Linux... so perhaps this card might be useful.
--Ya good point. I'll do some digging to see if it works with Ubuntu

$109.99 Corsair Micro ATX Case
Feels a bit expensive... I think you can find something for half that price.
--You're right, found one for 49.99 that I think will work great. N82E16811124150

Graphics Card: The other person we got some advice from was also nervous about our graphics capabilities. The Xeon processor doesn't come with integrated graphics so we will buy a graphics card something in the $100 range once we determine what type of connector our monitor uses.

Thanks again for your help!

Ian

[wyldckat]

Hi Ian,

Originally Posted by unh247

Thanks for getting back to me so quick!

You got lucky

Originally Posted by unh247

$339.99 Intel i7-4790K Processor
Are you planning on over-clocking this CPU?
--Since my earlier post we got some advice from another student who has done some CFD work and he recommended a 325.99 Intel Xeon E3-1271 V3 3.6GHz Quad-Core Processor and I think we are going to go with that such that we don't have to worry about overclocking.

I've got mixed feelings regarding that suggestion. Here's why:

• Xeon is great for stability and security, since it's designed to withstand 24/7 working endlessly at full capacity and it supports ECC RAM. The downside is that ECC memory requires a motherboard that supports it and you have to buy ECC memory modules, not standard modules... which cost a bit more.
• In addition, the E5 and above series of Xeon support quad-channel memory, in comparison with the dual-channel memory that those CPUs you've mentioned have got. Have a look at the specs for each CPU, shown at ark.intel.com - the "Max Memory Bandwidth" is very important for CFD.
• The i7-4790K has 400MHz more computational power than the E3-1271 V3.
• For almost the same specifications of the E3-1271 V3, you can get an i5-4690K that is around 100$ cheaper, which is 100MHz less powerful, but still leaves you some margin for doing a bit of overclocking, for covering a bit the lost performance... for example, upping by 200MHz. The downside is that it will require a bigger heatsink, but there are a few good air cooled ones for 30$-50$ or even less.

The idea to keep in mind is that for CFD, the HyperThreading feature that the E3-1271 V3 and the i7-4790K have got is pretty much worthless. Beyond that, it's up to you, because CPU speed is very important.

Preferably buying a computer right now for CFD would already be advisable to switch to the new DDR4 RAM and quad-channel memory CPUs (Xeon E5 series V3 or i7-5820K), but the total cost might be prohibitive

Have a look at this thread for some more details: http://www.cfd-online.com/Forums/har...tml#post520919 - and don't mind the thread title, because it pretty much demonstrates what happens if a person shoots 2 tires on a super-car

Originally Posted by unh247

$291.98 HyperX Ram DDR3 1600 (2x8gb)
What "CL" value does it have? CL9, CL10 or CL11?
--They have CAS Latency 10. Think it is worth it to shoot for 9?

CL10 is good enough. CL9 might be worthwhile only if it's "cheap enough" to acquire.

Originally Posted by unh247

$132.00 Western Digital 2TB HD
Feels a bit overly expensive... in comparison to the CPU... is it a special edition hard-drive?
--More advice since posting was to get a SSD. We compromised and are planning on going with a "Hybrid" 1TB 120GB SS Cache WD HD

For CFD, it really depends on how much disk activity your cases will have. What you need to weigh is how frequently and how much data is written and read. For example, if a 10 week simulation spends 1h in disk activity with a regular hard-drive, it doesn't make much sense using SSD for reducing 1h to 10 minutes for that same 10 week simulation.

You'll have to do some tests/calculations yourself, to see how much your simulations require disk-wise. Because it might make more sense to buy the 2TB drive or even 3TB, if your cases will require ~30GB of RAM for running the simulations, specially if they are transient simulations.

Originally Posted by unh247

Graphics Card: The other person we got some advice from was also nervous about our graphics capabilities. The Xeon processor doesn't come with integrated graphics so we will buy a graphics card something in the $100 range once we determine what type of connector our monitor uses.

It's a bit hard to suggest a good graphics card, but usually the 100-150$ price margin is what the video-game industry aims for the people that like playing games with reasonable graphical quality. Bellow that is usually aimed at the people that rarely play games or that don't care much about graphical quality.

Best regards,
Bruno

[evcelica]

I'm just wondering why you would be looking at CPUs with only 2 memory channels for CFD applications. I'd look at the i7-4820K or i7-5820K, as they have 4 memory channels, and would be much, much faster than the i7-4790.

[pbachant]

We talked about this a bit offline, but what do you guys think about buying a single server node for now, with the prospect of building a ~200 core cluster down the road? Would it be just as advisable to build the single machine listed above, put it in a rackmount case, then build more later, or buy a server off the shelf?

[wyldckat]

Greetings Pete,

It all strongly depends on the amount of time and effort you can invest... and the money that can be invested.

The configuration discussed here makes sense for a workstation, not for a cluster. If you want to go "cluster", then you should plan for the nodes themselves, the time/effort you're willing to spend and how much office space is available.

A few examples off-the-top of my head:

1. You could go cheap and each node could be an i5-4690 or something like that. Essentially, each node could have 4 cores (no HyperThreading), 8 or 16GB of RAM 1866MHz. In addition, buy a few DDR Infiniband cards and respective switch, in second or third hand on eBay or something like that. This would cost around 500-600 USD for each node, plus 300 to 1000 USD for the DDR switch. Problem is the time it would be necessary to set it up. From my personal experience, this is something that could easily eat up 20 to 80h setting it up, due to several reasons. Structurally, it depends on whether you rely on cheap ATX or mini-ATX towers, or if you build your own structure.
2. You could go semi-pro and buy a custom configuration of a rack set-up. This could easily eat up 2000-4000 USD per node, but it would require half the number of nodes, since each node could have something like a dual Xeon E5-2650 v3, 64GB of RAM, with Infiniband QDR or FDR. Again, this is thinking of a cluster. This will take around half the time of possibility #1. And occupies either the same or half or less the office space.
3. Or go Pro and call up some HPC provider and request an explicit cluster for CFD. This will save you a lot of time (up and running in 4-8h perhaps), but will cost you 120 to 200% in either one of the previous solutions.
4. Or go insane and buy a single 80000 USD workstation with 4 CPU sockets, 16-18 cores per socket (4*16 = 64 cores), and 512 GB to 1TB of RAM. This makes sense if you don't want to loose performance in communications, nor have to deal with network cables, nor have problems handling post-processing. The downsides are the price and if something fails within the tower, where you risk a considerable downtime, when compared to a cluster solution (where loosing one or two nodes is not the end of the world).

Best regards,
Bruno

[unh247]

An update on what we ended up going with. Thanks all for your suggestions and advice.

Intel Xeon E5-1630 v3 Quad-Core Haswell Processor 3.7GHz- $378.81
EVERCOOL NI2011E*9525EP 95mm Sleeve CPU Cooler- $15.99
SUPERMICRO MBD*X10SRI*F Server Motherboard - $287.99
Crucial 32GB (4 x 8GB) DDR4 ECC 2133 Server Memory - $453.69
SAMSUNG 840 EVO INTERNAL SOLID STATE DRIVE - $79.99
Rosewill 2.5" Mounting Kit for 3.5" Drive Bay - $7.99
Western Digital Caviar Blue 1TB 7200RPM 64MB Hard Drive - $89.89
AMD FirePro 2270 1GB DDR3 Workstation Video Card - $119.99
CORSAIR CX series CX500 500W POWER SUPPLY - $29.99
ARK 4U*500*CA Black 4U Rackmount Case -$89.99

Ian