How much RAM do I need?
In the process of pioneering the use of private BIM clouds in the building design industry, we at BIM9 have had to get up close and personal with every component in a computer and analyze how BIM technology uses them. Although we get a lot of questions about all parts of a computer, “How much RAM do I need?” is not only the most common, but also the most misunderstood and the one question most likely to be answered incorrectly.
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Instead of jumping straight to the answer, let’s take a step back and cover some basics about RAM. RAM is a form of computer storage with a very fast access speed. When you launch a software application on your computer, much of that software is loaded into RAM to allow the software to run much faster than it would if it were running from the hard drive. Additionally, when you open files on your computer, they are also loaded into RAM. This process of loading software and data into RAM is what allows the computer to run at optimal speeds.
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Given this, the actual amount of RAM you need is determined by how much space all of the applications and open files require to load completely into RAM. You can find this number by using Windows Task Manger to see how much RAM is being used once you have your software running and data files open. As you research this you’ll find different software applications require different amounts of RAM based on how the software was programmed and the size of the data files they create.
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When determining how much RAM you need for Revit you can use what we call “The Rule of 20” which is just a simple equation. Take the size of your Revit project, multiply it by 20 and the result is the amount of RAM needed to load that project. This equation is not 100% accurate, but it’s a great rule of thumb to use when determining your RAM requirements. If your Revit projects have DWG or RVT files linked to them you’ll also need to add the size of those files to your RAM total at a one to one ratio. Here is an example to help you understand how to determine the amount of RAM needed for your Revit workstation.
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Revit file size: 200MB (X 20) = 4,000MB or 4GB
Linked Revit file size: 200MB (X 1) = 200MB
Linked DWG file size: 50MB (X 1) = 50 MB
Amount of RAM required: = 4250MB or 4.2GB
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In addition to the requirements above, you’ll also need to take into account the needs of any other software you consistently run in the background, things like Outlook, Word, Excel, etc. Each additional application also requires RAM so the more applications you have running simultaneously, the more RAM you’ll require.
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One of the most common misconceptions about RAM is that adding more RAM to a computer will automatically make your computer run faster. This is often not the case. The only time more RAM affects computer performance is when you run out of RAM. When multiple applications and open files require more RAM than you currently have available, your computer uses the hard drive as a substitute for RAM. We call this process paging. When paging occurs, your computer runs substantially slower due to the time it takes to repeatedly read and write data to the hard drive. In this case, adding more RAM will speed up your computer since more RAM allows more applications and open files to run without the need for paging.
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Another common question that arises when discussing computer performance is; “Should I be using a 64 bit or 32 bit operating system?” Fortunately this one has a very simple answer. If according to your analysis above you need more than 4GBs of RAM, you must run a 64bit operating system. This is because 32bit operating systems only see a maximum of 4GBs of RAM regardless of the actual amount installed on the computer. So a computer with 8GBs of RAM running a 32 bit version of Windows is wasting 4GBs of RAM since the operating system cannot even see the extra RAM to make it available to the applications.
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When it comes to deploying a BIM9 private BIM cloud, “How much RAM do I need?” is a critical question as this is the biggest factor that will determine how many virtual users a single physical computer can support. By accurately calculating how much RAM each Revit user requires to load their various software applications, files and projects, we ensure each virtual user has enough RAM to run at maximum performance.
