Graphics Card (GPU) based render engines such as Redhift3D, Octane or VRAY-RT have matured quite a bit over the last years and are starting to overtake CPU-based Render-Engines.
But what hardware gives the best-bang-for-the-buck and what do you have to keep in mind when building your GPU-Workstation? What is the best Hardware and best GPU for rendering with Octane, Redhsift3D or VRAY-RT, that is affordable?
Since GPU-Render Engines use the GPU to render, technically you should go for a max-core-clock CPU like the Intel i7 7700K that clocks at 4,2GHz.
That said though, there is another factor to consider when choosing a CPU: PCIE-Lanes. GPUs are attached to the CPU via PCIE-Lanes on the motherboard. Different CPUs support different amounts of PCIE-Lanes and Top-tier GPUs run on 16x PCIE 3.0 Lanes.
The i7 7700K has 16 PCIE-Lanes meaning you could just use one GPU at full speed with this CPU. If you want more GPUs you would need a different CPU that supports more PCIE-Lanes like the i7 6800K (28 PCIE-Lanes) or the i7 6850K (40 PCIE-Lanes).
GPUs though can also run in lower speed modes such as 8x PCIE 3.0 Speeds and then also use up less PCIE-Lanes (8x). Usually there is a negligible difference in Rendering Speed when having GPUs run in 8x mode instead of 16x mode.
This would mean you could run 2x GPUs on an i7 7700K in 8x PCIE mode, 3x GPUs on an i7 6800K and 5x GPUs on an i7 6850K.
When choosing a CPU you should also consider the following: When actively rendering, GPU renderers are of course mainly dependent on CPU performance.
Some processes though that happen before and during rendering rely heavily on the performance of the CPU, Hard-Drive and network.
For example extracting and preparing Mesh Data to be used by the GPU, loading textures from your Hard-Drive and preparing the scene data.
In very complex scenes, these processing stages will take lots of time and can bottleneck the overall rendering speed, if a low-end CPU is employed.
Best Graphics Card for Rendering
To use Octane and Redshift you will need a GPU that has CUDA-Cores, meaning you will need a NVIDIA GPU. VRAY-RT additionally supports openCL meaning you could use an AMD card here.
The best bang-for-the-buck NVIDIA cards are 1070 GTX (1920 Cuda Cores, 8GB VRAM), 1080 GTX (2560 Cuda Cores, 8GB VRAM) and the 1080 Ti (3584 Cuda Cores, 11GB VRAM).
On the high-end, the currently highest possible performance is offered by the NVIDIA Quadro P6000 that also comes with 24GB of Video RAM. GPUs, that have 12GB Video RAM and more, can handle high-poly scenes with over 200 million unique objects best.
Founders Edition Blower Style Cooler
- PRO: Better Cooling when stacking more than one card
- CON: Louder than Custom Partner Card Cooling
Custom Partner Cooling
- PRO: Quieter than Blower Style, Cheaper
- CON: Worse Cooling when stacking cards
- PRO: Best All-In-One Cooling for stacking cards
- CON: More Expensive, needs room for radiators in Case
- PRO: Best temps when stacking cards, Quiet
- CON: Needs lots of extra room in the case for tank and radiators, More Expensive
Be sure to get a strong enough Power supply for your system. Most Cards have a TDP of around 180-250W. CPU of around 100W and any additional Hardware in your case.
I Recommend a 500W for a One-GPU-Build. Add 250W for every additional GPU.
Make sure the Mainboard has the desired amount of PCIE-Lanes and does not share Lanes with Sata or M.2 slots. Also be careful what PCI-E Configurations the Motherboard supports. Some have 3 or 4 PCI-E Slots, but only support one x16 PCI-E Card.
You’ll need a 1151 type Socket for a Kaby Lake i7 (e.g. 7700K) type CPU and a 2011-3 Socket Mainboard for a Broadwell-E type i7 CPU (6800K, 6850K, 6950X).
My best bang-for-the-buck recommendation for LGA 1151 Boards is the Asus Prime z270-A and the Asus X99-M WS/SE Intel X99 for 2011-3 CPUs.
What Hardware configurations are you eyeballing with, or have already been able to test? Share your thoughts in the comments!