[arsalan.dryi]

Hi all,

I want to buy a new pc/workstation for my master thesis, because the cpu time of the simulations is so high that i can't use may laptop for any other purposes.

I'll use this PC for two and three phase flow simulations using a modified interFoam solver with a custom time varying bodyForce. the number of cells is about 3 to 5 millions (still not clear). The other uses include dynamicMesh, snappyHexMesh, solidWorks and drawing.

So with these purposes, what do you think about the configuration that i can buy with a moderate or maybe low budget?

In the other word, the CPU, Motherboard, Hard disk, RAM, GPU, Power supply and Cooling system must have what features and characteristics?

Thanks in advance.

Best Regards,
Arsalan.

[scipy]

CPU - Core i5-6500 - 195 € (or 6600K if you want to overclock and buy a better cooler)
MBO - H170 chipset with 4 DIMMs (or Z170 if you go with a K processor, for example MSI Z170-A Pro) - 100 €
RAM - DDR4-3000 2x16 GB or 4x8 GB CL14 or CL15 (32 total, otherwise you won't be able to get ~5 million cells mesh in there) - 160 € (4x8) or 190 € (2x16)
HDD - single SSD as a boot drive, if you've got the cash go for a 256 GB M.2 drive like Samsung SM951-NVMe (works with MSI Z170-A Pro from personal experience), if not get a regular SATA3 SSD of 256 GB (synchronous MLC, 5 years warranty.. any Corsair Red, Intel 335, Samsung Evo etc) and a larger storage drive 2 TB or so (WD Blue/Red or anything similar) - 130 € for M.2 or 80 € for SATA3, storage drive ~90-100 €
GPU - ATI FirePro W4100 (or W2100) this is gonna be enough for smooth meshing, post processing and SolidWorks CAD work - 160 €
PSU - Anything really.. I'd go with at least a Corsair 450W or equivalent (get something that has at least 5 years warranty, modular if u want, but not needed for this kind of a system - I got a VS450 from Corsair and have no qualms) - 40 €
CASE - Anything.. not important. 1 exhaust vent is enough for this kind of a system. Corsair 200R is kinda nice, elegant, no LED lamps and shit and just 50 €.

Total = 1000 € (for K, Z chipset, M.2 SSD) or ~100 € less for other one.

That's currently best bang for the buck...

[arsalan.dryi]

Originally Posted by scipy

CPU - Core i5-6500 - 195 € (or 6600K if you want to overclock and buy a better cooler)
MBO - H170 chipset with 4 DIMMs (or Z170 if you go with a K processor, for example MSI Z170-A Pro) - 100 €
RAM - DDR4-3000 2x16 GB or 4x8 GB CL14 or CL15 (32 total, otherwise you won't be able to get ~5 million cells mesh in there) - 160 € (4x8) or 190 € (2x16)
HDD - single SSD as a boot drive, if you've got the cash go for a 256 GB M.2 drive like Samsung SM951-NVMe (works with MSI Z170-A Pro from personal experience), if not get a regular SATA3 SSD of 256 GB (synchronous MLC, 5 years warranty.. any Corsair Red, Intel 335, Samsung Evo etc) and a larger storage drive 2 TB or so (WD Blue/Red or anything similar) - 130 € for M.2 or 80 € for SATA3, storage drive ~90-100 €
GPU - ATI FirePro W4100 (or W2100) this is gonna be enough for smooth meshing, post processing and SolidWorks CAD work - 160 €
PSU - Anything really.. I'd go with at least a Corsair 450W or equivalent (get something that has at least 5 years warranty, modular if u want, but not needed for this kind of a system - I got a VS450 from Corsair and have no qualms) - 40 €
CASE - Anything.. not important. 1 exhaust vent is enough for this kind of a system. Corsair 200R is kinda nice, elegant, no LED lamps and shit and just 50 €.

Total = 1000 € (for K, Z chipset, M.2 SSD) or ~100 € less for other one.

That's currently best bang for the buck...

Hi Alex,

First. I thank you very much for your attention and the fast reply.

Could you explain more about the CPU characteristics which you offered and the RAM relationship with the number of mesh cells?

Best Regards,
Arsalan.

[scipy]

CPU is the fastest 4 core you can find... i7 of the same socket is unnecessary since CFD multithreaded applications don't need the fake logical cores of the hyperthreaded i7's.

As far as RAM goes, you get the fastest possible RAM since the connection speed between the CPU and the RAM is the biggest bottleneck in CFD. Size wise, I currently have 16 GB of RAM and that limits me to around 4 million cells in single precision (with a coupled solver, with a segregated solver it'd be 5-6 million). So, 32 GB of RAM will give you a nice cushion to either be able to run some grid independence studies, or to just have enough RAM so that you can run your simulations on 3 cores and still have 1 core (and enough RAM) to post-process, pre-process or do some CAD work while running CFD.

[arsalan.dryi]

Originally Posted by scipy

CPU is the fastest 4 core you can find... i7 of the same socket is unnecessary since CFD multithreaded applications don't need the fake logical cores of the hyperthreaded i7's.

As far as RAM goes, you get the fastest possible RAM since the connection speed between the CPU and the RAM is the biggest bottleneck in CFD. Size wise, I currently have 16 GB of RAM and that limits me to around 4 million cells in single precision (with a coupled solver, with a segregated solver it'd be 5-6 million). So, 32 GB of RAM will give you a nice cushion to either be able to run some grid independence studies, or to just have enough RAM so that you can run your simulations on 3 cores and still have 1 core (and enough RAM) to post-process, pre-process or do some CAD work while running CFD.

Hi Alex,

One more question about the CPU, should I use the 6600K and overclocking (for better cooling and saving time) or the 6500 model would be enough? Are these models very different?

I prefer to use a model that I have fewer problems in the future (of course, also depends on the price difference!!)

Thank you so much.

King Regards,
Arsalan.

[scipy]

They are basically the same CPU, the 6600K has unlocked multiplier and can be overclocked. However, 6600K is 40 € more and doesn't come with a cooler - so you have to buy one. Now, since overclocking raises the temperature you need better cooling.. if you don't plan to go overboard (like chasing more than 4.2 or 4.4 GHz), you can pretty much be ok with air cooling (something like Scythe Katana 4 or similar) for ~20 €. Some people go for the water cooling such as Corsair H100 or whatnot.

Aaaanyway, I've overclocked a i5-3570K (this same CPU two generations ago) all the way to 4.4 GHz and ran benchmarks. It's not worth it... a 30% raise in frequency yields about 6% gain in iteration time.. with all the cooling costs and the extra energy consumption CPU overclocking isn't really all that productive. Higher RAM speeds on the other hand... much more gains (but that's why you'll get the fastest RAM possible in the first place).

So, just shut up, stop overcomplicating and asking too many questions. Get the i5-6500 and go do some CFD.

[flotus1]

Speaking of memory speed: you will need a Z170 chipset in order to use RAM with frequencies higher than DDR4-2133. Which is what I would recommend for CFD. Avoid Asus mainboards, they tend to have difficulties with faster RAM. H170 and all other Skylake chipsets do not allow to set memory speeds higher than DDR4-2133.
The next best (and more expensive) option is still Intels X99 platform with a Core I7-5820k.
However, the actual best bang for the buck in terms of CFD performance might be a used workstation with dual-Xeon processors from ebay for 800-1000$.

[scipy]

This is true! Z170 and fastest RAM possible.

I didn't even think of used hardware.. going soft in the head these days Yes, that's a great option. If it's for personal use you can find some very decent quality sample (engineering sample) Xeons. I think last time I investigated this, the best "bang for the buck" was an E5-4617 in dual config. These CPUs ran for about 200$ a piece (QB85 versions) and you got 6 physical cores (12 for two CPUs) capable of 3.2 GHz on all-core turbo mode. Two of these, Z9PE-D8 motherboard, 8 sticks of DDR3 and you're set (Xeon E5 non-V2 will not see anything faster than 1600 MHz DDR3). If you're not buying a whole PC (most times these are sold as internals: mbo + cpus or maybe even ram), make sure to get a E-ATX case which can fit the motherboard. I'm quite partial to the old Coolermaster Stacker which can be found online for about 50 bucks these days. Power supply also needs to have 2 x 8-pin ATX12V for two CPUs (most PSUs over 750 W have this, just make sure).