I'm running a Mac Pro with 32Gb RAM. I'm thinking I'll bump that to 64Gb (about $400) but wondering if I should go to 96Gb (about $850)? Thoughts on 32 vs 64 vs 96? Also, anyone know Houdini's upper limit to addressing available RAM?

Depends if you're doing simulation work or not. I remember seeing people get 128 or even 256 gb ram for sim machines. I think Houdini would utilize as much as you have. Again depends on how big your sims are.

Yeah, I think LLFAs first word sums it up - “Depends”.

I'm no expert in how to improve ones rig for using Houdini, but here's what I noticed so far when I was considering more ram for my system.

One part of my project made heavy use of ‘complicated’ object movements using chops. Alot of that work was also done in VEX ( which is known to be lightweight - but I took advantage of that and made ‘heavy’ use of it.).

The result was very slow cook times which put my workflow to a crawl as far as tweaking my settings for motion and position adjustments of my objects.

This is when I started looking into getting more RAM. But as I read I realized the cooking part had more to do with my processing power. Fine I thought, I'll look into parallel processing and came across some boards ( one offered by Intel although expensive) that seemed to be a solution, and also different strategies.

But then I came across some older forum discussions on this topic and read that although there are processes that could benefit from parallel processing there are some ‘routines’( in Houdini ) that by necessity need to be single threaded.

So I thought I'll leave it as it is until I become more knowledgable of what Houdini does or doesn't do in terms processing. ( The performance monitor under Houdinis window tab is a good tool to see where in your network what is taking up the most resources - I also make use of windows task manager processes window ).

I continued my project and started making some sims which only added to the cook times even more which is when I got into how to cache out.

What I learned from caching out is that it does take some of the pressure off the cooking but then I really need the RAM.(also disk space, depending on how I cache out ).

I also then realized which I haven't done yet, I could do a geometry cache where I was originally experiencing slow cook times.

So it's like LLFA says, depends on whether your doing simulation work or not.

And there is also the distinction between simulation and caching out. You can do simulations without caching out but I can't say on simulation alone what is being made more heavy use of - processing or RAM.

In my case, I noticed caching really maxed out my RAM fast; disk space as well but for myself that is easy to accomodate.

So getting as much RAM as you can is not a bad idea(to me). But depending on what you do will determine if it actually gets used; In my projects I can easily use up as much RAM as I can throw at it.

Another consideration too is when it comes to rendering. Pretty sure that can use up much RAM as well but I'm not sure ( after scene cooking has been ‘done’ ) how much processing is involved vs. use of RAM.

Thanks guys. According to Activity Monitor, I max CPU way before RAM gets filled most of the time (pyro, destruction, rendering) which surprised me. I'll throw some fluid sims at it today and report back.

The more RAM you get, the more you will notice how fast the RAM is. I've worked on a machine with cheap slower RAM (but lots of it) and definitely would notice a (not so)brief freeze whenever Houdini would clear the cache.

So RAM speed will come into play as well.

Thanks JP, I ordered OWC RAM which gets solid reviews.
Kevin