I would not knowingly run a computer with bad RAM. Anything can happen from a silent problem, to blue screens, down to a corrupted hard drive.
Many Linux distribution install disks, such as “Mint” with “Cinnamon” include MemTest86, the defacto standard for memory testing. For your purposes, avoid installing anything, such as the operating system itself. When in doubt back up your computer first.
In Windows, you can CTRL-ALT-DELETE, your computer once, which opens the menu,
from which you can choose Start Task Manager. You can click on the Performance tab, to see how much memory you are using.
(In the screenshot, I am rendering, which drives up the memory usage, in this case about 3 times as much as when not rendering.)
You can minimize task manager.
Start Rhino. Load a large project.
Maximize Task Manager again.
Click on the Processes Tab in Task Manager.
From here you can see how much memory Rhino is using, or in this case Firefox.
Rhino is pretty efficient for memory usage, and doesn’t seem to leak noticeably.
Rendering does take a lot of memory. For a large project, you may be able to work, but not render.
If you have enough RAM, your machine won’t use virtual memory much*, or run out.
If you run out of real RAM, your machine will use the hard drive for virtual memory, which will slow down things unbearably.
Large textures use more memory than anything on a video card. So, unless you have a lot of textures, your video card will likely be fine, unless it’s an Intel Integrated GPU.
*Lastly, if you don’t have a SSD, Windows will use virtual memory even when it doesn’t need to, which slows down your computing experience. Both of my machines have virtual memory deactivated.