Mixing Fast and Slow nodes for DBR?

[Streetwise]

I'm thinking about adding one or two fast Xeon nodes to two existing nodes (i7 3930). Are there any pitfalls in mixing old with new (slower with faster) in terms of how renders are processed via DBR? I'm on 2.4 now, but plan to upgrade to 3 very soon. Most of my work are large stills, but there's always the occasional animation.

Thanks.

[Donald2B]

Just be careful when you are in a hurry...sometimes the slow nodes can get stuck and extend the rendertime by 5-10 minutes, or longer, waiting on those buckets to finish. We haven't upgraded to VRay 3, yet, so I don't know how well the new system works in production. In VRay 2.50.01 it can be a LONG wait on those last few buckets.

[werticus]

vray 3 has the bucket splitting which really helps, but you can still get buckets stuck if there is a particularly difficult bucket near the end before the buckets split up, so you have to pay attention to which direction the render goes. (eg top to bottom or bottom to top or left to right etc)

a 3930k i7 is likely to process the LC pass faster and start sooner, and in fact probably have a faster per bucket speed than a xeon but the xeon will have faster overall performance due to more buckets. I think you'll actually find the xeon's holding up the renders more at the ends in this case.

[Streetwise]

Werticus, what you said in your last sentence makes me wonder now if I'd be farther ahead to get a single i7-5960 CPU over 2 x5670's? The price on used Z800's seems pretty attractive which is why I was looking at them. Hmmm what to do...

[Streetwise]

Another thought: Is it generally not good to mix i7 nodes with Xeon nodes? When I can add a 2x X5670 setup to the mix for $750+/-, that's pretty darn attractive. Just worried that performance would suffer if combined with existing i7 3930's.

[Donald2B]

Honestly, at the end of the day, the best thing you can do is just work the numbers out.

Look at the many benchmarks and get a general idea of the speed of the different options. Calculate the cost and how much power they will utilize and then buy the cheapest option for you.

We have Xeons and iCore 7 machines here as workstations depending on the work each person needs to do. Our farm is entirely Xeon due to power and space constraints. They give us the most horsepower in the smallest possible space utilizing the least amount of power. But all of that comes at a little higher price than other options.