Ram is used to store all the data Vue needs to compute the render ( the textures, the objects, the lighting informations, the bump/displacemnt effects..., and all the apps and utilities that are needed to make your machine work, including Windows/Mac OS, and Vue of course), so the more you have, the less you'll get of memory error messages, but having more ram won't speed up the render ( it will a tiny bit only if your memory is slow), CPU power is the key.
Now the problem you ran too makes me think like Peggy, your machine might be overheating, or maybe there is a problem with your power supply.