We would like to provide some hints as to what system to get by explaining the factors that come in play:
CPU: When you load content a fair amount of CPU calculations are made to apply morphs, fit clothing, smooth and deform. It is one of the factors involved in loading time (along with storage speed). The CPU is also 100% of your render performance (render time) when using non GPU accelerated renderers (like 3Delight in DAZ Studio). So if using DAZ Studio 4.7 or older your CPU determines how fast your renders happen as well as has an influence on how fast things load and deform.
Storage speed: Your hard drive speed does play a role when loading content but only to a certain point. A spinning disk (regular hard-drive) is quite a bit slower than an SSD so I would recommend getting a 520GB or 1TB SSD to host your DAZ content and scene files on. This along with CPU speed determine how fast things load in your scene. If you raid spinning disks you do get more bandwidth but access time stays slow therefore a raid of spinning disks will not be as fast as even a single SSD. It’s not just about bandwidth MB/s, it’s more about latency (how quickly data seeks happen) and an SSD is much quicker than spinning disks. Storage has no (or negligible) effect on render time.
GPU (Graphics Processing Unit): With the latest public beta (DAZ Studio 4.8) the GPU plays a HUGE role in the render time when using Iray (the default renderer in DS 4.8). The GPU plays two roles, it determines how fast you can move geometry around in the interface and it adds processing power to the render process (reduces render time) with Iray (included), Octane (plugin) and Reality (plugin that uses Lux render). Let’s ding into the GPU as a few factors come to play.
- GPU memory has no direct effect on render time, it simply determines how big a file you can work with. We found that 2GB can handle a single character with a medium sized environment, 4GB can handle around 4 characters and a scene so we recommend 4GB and up. If you have two GPUs and they have 2GB each it does not add up to 4GB, each card has to hold the entire scene. If you try to render a file that is too large to fit in the GPU, Iray will use the CPU to render (which will be much slower than using a GPU or both GPU and CPU together). So GPU memory is what determines if the GPU can be used or not, if the file fits, it will be used and if the file doesn’t fit, it won’t.
- GPU cores, this is similar to CPU cores but instead of having 4,6 or 8 cpu cores running at 4000 MHz, you have thousands of them but they run at around 7000 to 1200 MHz. Each core can calculate a par tof the image so render time (with a gpu based renderer) is directly proportional to how many cores you throw at it. Iray is an NVIDIA technology and uses CUDA cores which are found in all NVIDIA GPUs, This means AMD (or ATI) GPUs will NOT be used for rendering with Iray, they will however come into play in the OGL viewport when you orbit around your scene (in drawstyles other than Iray). You can use one or multiple NVIDIA Geforce, Quadro and Tesla cards (or a mix of Quadro and Tesla) to decrease your render time with Iray and current cards tend to range from 250 to 3000 CUDA cores so there is a huge range of performance (and pricing) to pick from. The biggest setup that is available today as I write this would be using four NVIDIA Geforce Titan X cards which would give Iray a total of 12,288 cores to render with and 12GB per card would accommodate very massive scene files. Even entry level cards with 300 or 400 cores are substantially faster at rendering than current high end CPUs.
- There is no tangible difference in render time between Quadro, Tesla and Geforce cards, the specs that matter are how many cores and how quick they are (Geforce tend to be a little faster).
To decide what computer to go with I would use the following guidelines:
- Make sure your motherboard has the latest Intel chipset (currently the X99)
- For graphics applications 32GB of RAM is a good minimum, most high end systems have 64GB but this will have little to no impact on your render time.
- 6 core CPUs are enough if you are going to use Iray (or other GPU renderer), when you get into high core count GPUs, the CPU becomes less important.
- Get as many large GPUs as you can… 4GB or memory is a minimum, over 8GB is probably not going to be needed. Core count is critical, so if two less expensive cards give you more cores than one expensive card, go for the two cards…
· Make sure your motherboard offers at least 8 lanes of PCI per GPU installed (Ideally 16 lanes per GPU). If you have 16 lanes per GPU you get the full performance, having only 8 lanes per GPU gets you around 80% of the GPU performance, this influences the decision to buy one large card over multiple smaller cards.