# Computational physics desktop

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1. May 29, 2015

### Goldberry

So, I'm going into my senior year in college. I'm a physics major working on computational physics research - lots of enormous sets of data and multi-dimensional modeling. I'm also applying to phd programs for when I graduate.
I have a $1500 grant for use in my research, so my PI has told me to get myself a good computer. My laptop's light & fast, generally, but not so good at the heavier duty stuff. So: what should I look for in a desktop? Any advice on specific ones? 2. May 29, 2015 ### Greg Bernhardt ### Staff: Admin Is the$1500 all for the desktop? If so, you can get a very powerful machine for that much if you can build it yourself. Are you tied to a specific OS? I think min specs for your Win/Linux machine would be 12GB RAM, i7 processor, NVIDIA Quadro graphic card and an SSD HD.

3. May 29, 2015

### Goldberry

If I want it to be. I don't have much else to do with it, and it's not through the lab so there's nowhere else really to put it.

I don't have strong feelings about which OS at all.

4. May 29, 2015

### robphy

Early on, I used to build desktops from parts that I chose...
but after a while, I got tired of dealing with all of that shopping, assembly, configuration, etc...
and instead just watched deal-sites (for a good enough desktop from Dell or HP).

It could certainly be the case that a new typical desktop is sufficient for what you want to do...
but if you need more...
[It's been a while since I've shopped for a desktop]

I stumbled upon this vendor [which I know nothing about]
http://www.xicomputer.com/products/mtowerxeon.asp
whose possibly-overwhelming configurator
http://www.xicomputer.com/products/Configure_prof.asp?model=mtowerxeon&configid=
can give you a sense of options: specific parts and specific prices.

Depending on the nature of your computations [and your software and operating system],
you probably have to compare the available features [weighted by price]...

CPU is important (Xeon vs i7?, large cache-size, number of cores, etc...)
lots of RAM is important (I thought 16GB was a lot until I saw that configurator)
Nvidia graphics card (to use its GPU.... on my to do list of things to learn about: using the GPU for computation)
I prefer to go cheap on the display (usually no [new] monitor) and spend my money on the other computational parts.

Possibly biased: http://www.nvidia.com/object/justthefacts.html

Again, it could certainly be the case that a new typical desktop is sufficient for what you want to do.

5. Jun 4, 2015

### enorbet

I think you might want to ask some questions as to how much multi-dimensional modeling you will need to do because that is pretty much all video card and while Quadro is certainly the best, you need to know how much you need to spend there to determine what is left for the rest. There are Quadros that cost over $12K !! There is a pos that is$150. A limited but usable Quadro can be had for roughly $500 but apparently the sweet spot is closer to$1K.

If you have any experience with installing peripheral cards I recommend you try to build your own since that way you can get the all-important video card of your choice. Also, apparently due to diminishing desktop share, Dell, HP and others are somewhat less reliable than they used to be and they often use proprietary parts and/or skimp on PSU since most people are unaware of how important it is (Everything depends on it). All cabling has keyed connectors so you really can't make a mistake and you can get exactly what you want, no more and no less. There are also helpful tutorial videos out and about. With just a little care it is easy and it can even be fun. There is also that slightly intangible sense of confidence that comes from knowing "what's under the hood".

Regarding OpSys - You might want to consider what sort of work you want to do upon graduation. Windows enjoys a 90+% market share on the desktop so at least at the workstation level it is likely to be a player for many years. Linux has ~90% market share on supercomputers and ~60% on enterprise servers and that seems to be growing so what you choose depends on your professors requirements and your aims for the type of work you wish to do later. Here again the deciding factor might be CAD because modeling apps area is not quite as rich in Linux as in Windows though Matlab is available for both and due to increased use in the Sciences CAD support is growing rapidly.

Stitch in time - check with what your course/professors recommend or require, then apply your own preferences within that.

6. Jun 4, 2015

### JorisL

To add to this, when you plan to program a lot, Linux (Unix-based? Don't know how easy the terminal on Mac works) is the way to go.
On Windows you usually go for an IDE which obscures some important parts of the process i.e. compiling.

7. Jun 5, 2015

### CalcNerd

While you can certainly get a more powerful desktop for the money, you can probably buy a refurbished (returned system replaced by company with in warranty ie 2-6 months old, with a cosmetic blemish).

Buy one with a 3D graphing card (2 gig card perhaps), 1 terabyte drive (or 256-500 Gig SSD), a high end CPU with the ability to manage 16Gig (or simply buy the Laptop with 16 Gig, but this might push your cost up $3-400.). This system can be bought via mail order in the USA for around your budget as a refurbished system. A high end CPU probably means a laptop with two hours of battery time, but the laptop versions of intel's CPU's were (and may still be) constrained to 8 gig (my laptop uses an i7 with built in 3D which is fast, but would not compete with a real graphics card and the intel CPU (hence my laptop) won't address more than 8 gig. Still, my system is very fast to boot with an SSD drive and is a nice system and I bought refurbished for half the cost of new. That is why you might even consider a high end AMD CPU for the system. All the big name laptop manufacturers have refurbished systems for sale (in the USA anyway). I like a portable system so that you can take it with you on a whim. Many systems have a docking station option for about$100. That usually allows you to have lots of additional ports that may not be available on the laptop itself. Not all laptops support a docking station, but high end systems generally do.

Response to quote: Laptop CPU's are all low power devices in comparison to normal CPU's to provide lower power consumption to allow for 6-8 hour battery life. My i7 CPU is a low power CPU, but it came at a price, it is crippled and cannot address more than 8 gig, nor does it have any ability to add a graphics card vs some laptops (15-17 inch range) can be purchased with graphics cards and often have the desktop type CPU installed. These are battery hogs, heavy, and big, but they do offer a mobile solution.

Last edited: Jun 5, 2015
8. Jun 5, 2015

### JorisL

2-3 years ago this was true, not so certain about it now. There are laptops with an i5 etc which reach 7-10 hours (browsing but mine would manage that like 2 hours tops) so maybe 3-4 hours is more in the ballpark. Secondly if you really need it on the go you could get an extended battery pack.

If you are determined to get a desktop, make it a great one.
On the side you can buy a simple laptop/netbook whatever it's called today(chromebook, ultrabook, dozens of things I don't know about) so you can SSH into your desktop for the more constraining work.
With Linux that should be quite easy, even for a beginner as there is a lot of information out there.

9. Jun 7, 2015

### rbelli1

Since you plan on doing computation heavy research you might just consider saving the money for time on some big iron.

You can write the programs on any old computer, cell phone, etc. and use the more powerful server farm to do the heavy lifting.

BoB

10. Jun 8, 2015

### cgk

@OP: I don't think a Quadro is the way to go. With a gaming-grade GPU rather than a professional-grade GPU you get much more bang for the buck. The same applies for most other components (e.g., a quad-core i7 runs circles around a similarly priced Xeon). So unless you actively need GPGPU stuff (chances are >95% that you don't), just getting a good gaming PC is equivalent to getting a good number crunching PC (if you don't mind fancy grills and heat sinks in your hardware). You might need some extra memory, so make sure you get a board into which you can put 32 GB (these cost ~180-250 USD at the moment, depending on speed).

So: Get a quad-core i7 (not a Xeon), a gaming-grade discrete AMD or nVidia graphics card (use nVidia if you want to run linux, nVidia linux drivers are better and easier to handle; for Window's I'd go with AMD at the moment), and some memory. With memory: Be aware of the requirements of the CPU and the chipset. If you should get a quad-channel CPU (e.g., some big Xeons), it will be severely slowed down unless you get equal RAMs in batches of 4 (e.g., for quad channel, you'd make 32 GB as 4x8 GB, and 2x16 GB would be slower).

Also, it is a good idea to get a good monitor. Spending 200 extra dollars on a 4K display will be absolutely worth it if you code on it frequently.

EDIT: Also, if you run scientific applications using linear algebra (BLAS/LAPACK), you should make sure that you get a CPU with supports the AVX 2 instruction set (starting at Haswell, Sandy Bridge and Ivy Bridge do not have it. Of course any new CPU will have it, but refurbished PCs might not).

11. Jun 12, 2015

### CalcNerd

Actually Dell makes a line of high end gaming laptops (hence High end 3D video systems) called alienware. They offer these on their website as refurbished too. The refurbs are often returned items due to a previous owner not liking screen size or weight ie too small of screen so moves up or weighs to much and exchanges for smaller etc.
Dell also has business class laptops (I am working on one now) that has dedicated video cards to optimize graphics when using CAD or other graphic intensive modeling. These systems may even be in your price range and can be purchased with 16-32 Gig or possibly even more.