Problem Description

Solution

Processor

COMSOL Multiphysics is available in 32-bit and 64-bit versions on a number of different platforms, and includes parallel processing capabilities. For details see the system requirements at http://www.comsol.com/products/requirements.php.

A number of web-sites publish performance figures for CPUs, for example, http://www.spec.org/benchmarks.html. COMSOL does not track and measure the performance of individual CPUs and motherboards. In addition to the above information you can request benchmark figures from your computer vendor.

The Windows, Linux and SUN versions of COMSOL Multiphysics 3.4 include full support for multicore parallel processing. Running on supported multicore platforms will speed up the computations considerably if you address multiple cores. See details in Solution 1001.

A CPU with a larger cache sometimes gives a noticeable performance increase. However, CPUs with a larger cache are often significantly more expensive. For COMSOL Multiphysics, it normally pays off better to invest in a faster CPU than in a slower one with a larger cache.

RAM

64-bit platforms

We recommend any user with sizable models to use a 64-bit platform. Since a 64-bit architecture can address much more than 4 GB RAM, COMSOL Multiphysics can be used without the memory limits imposed on 32-bit systems (see below). You can thereby make full use of all the physical memory that you put into your machine. To benefit from the 64-bit version of COMSOL Multiphysics, you need both a 64-bit hardware platform and a 64-bit version of the operating system. Even if you have smaller models, a 64-bit computer is to prefer, since it does not suffer from fragmentation issues that some 32-bit platforms do. Currently there is no 64-bit version of COMSOL for the Mac OS X platform.

32-bit platforms

On 32-bit platforms the maximum theoretical address space is 4 GB. On Windows it is normally divided so that applications can use 2 GB and the remaining 2 GB is reserved for the operating system. On Windows 2003 Server and Windows XP Professional you can make use of the /3GB switch in boot.ini in the operating system to allow a single process to allocate up to 3 GB of memory instead of the normal 2 GB. See the details in solution 1030.

Linux, SUN and Mac OS X only reserve a small part of the memory for the operating system. This means that you will be able to use closer to the maximum 4 GB that can be addressed on 32-bit platforms.

Computations in COMSOL Multiphysics can potentially be memory intensive. However, buying more memory than you can address from a single process is not worthwhile for COMSOL Multiphysics in 32-bit mode. Thus, more than 2 GB (or 3 GB with the switch) on Windows and 4 GB on Linux/UNIX cannot be utilized by the 32-bit versions of COMSOL Multiphysics. When buying a computer, check that the motherboard supports the amount of memory that you require and that additional memory modules are not excessively priced.

On 32-bit Windows platforms, memory fragmentation can be a problem. This means that you may get an out-of-memory error even though you apparently have available memory left. The reason is that no contiguous memory block is available. Once again, should you encounter out-of-memory problems, we strongly recommend that you migrate to a 64-bit system (see above).

Graphics card

Most modern computer graphics cards for Windows support OpenGL or DirectX 8.0 which is required by COMSOL Multiphysics. The graphics quality in COMSOL Multiphysics is slightly higher when using OpenGL. Many mid-range graphics cards have a DirectX implementation that is more robust than the OpenGL implementation.

COMSOL has tested several mid-range priced NVidia GeForce and ATI Radeon-based graphics cards for stationary computers with Windows XP and Windows Vista with good results both with DirectX and OpenGL. Note that the graphics chips available in laptops often are not that well suited for 3D graphics. Our recommendation is to buy a desktop computer if you do not have other strong incentives to buy a laptop computer.

General

Hard disk performance does not make a large difference to the computational performance of COMSOL Multiphysics, unless the computation relies on virtual memory. The time it takes to start COMSOL Multiphysics is however significantly influenced by the hard disk performance.

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