Home → Troubleshooting → @RISK for Excel: Simulation → "Not enough memory to run simulation"
Applies to: @RISK 5.x and newer
With multiple CPU enabled, when I run a simulation the Performance Monitor displays the error message "Not enough memory to run simulation". What is wrong, and how can I fix it?
The simulation is not able to allocate the memory it needs to run the simulation. This is probably not a problem with physical RAM, but with virtual memory. Please see Virtual Memory Settings for guidelines, and instructions on changing the settings.
Here are some additional possibilities:
Disk free space — Virtual memory uses the free space on your hard drive, so make sure that is not constrained. You may want to use the CLEANMGR program (part of Windows) to remove temporary files: click Start » Run, type CLEANMGR and click OK. If you clear out files manually, remember to empty the Recycle Bin.
Smart Sensitivity Analysis — If your Excel file is many megabytes in size, precedent tracing (Smart Sensitivity Analysis) may actually exceed the available memory. Try turning off Smart Sensitivity Analysis on the Sampling tab of Simulation Settings.
64-bit Excel — For most people, 32-bit Excel is just fine. But 32-bit Excel is limited to a 2 GB memory space (or possibly 3 or 4 GB; see Large Address Aware), regardless of how much physical RAM you have. If you have a really large simulation, you may need 64-bit Excel. One symptom would be a simulation that runs with a modest number of iterations but gets "Not enough memory to run simulation" when you specify a large number of iterations. See also: Should I Install 64-bit Excel?
See also: "Out of memory" gives more suggestions for reducing memory use.
Last edited: 2018-02-12