CPU and GPU price-performance analysis
We've witnessed some exciting developments in the desktop computing space recently, particularly the new Threadripper CPUs from AMD (and price cuts to their existing models) and RTX GPUs from Nvidia.
Phoronix tested IndigoBench on a RTX 2080 Ti, and - somewhat predictably - it was an absolute monster for GPU path tracing, even without using the new RT units! There are lots of good reasons why the Turing architecture is well-suited to Indigo's GPU engine, particularly the separate integer units. Unfortunately we had no advance notice about RTX and have yet to obtain RTX hardware for testing and development, however this is of course something we will look into now that it's released.
We also have IndigoBench results for the new 32 core, 64 thread AMD Threadripper 2990WX overclocked to 3.5 GHz, as well as results from the previous generation Threadripper 1920X with 12 cores, 24 threads; the significance of the latter is that you can now get 4 memory channels, tons of PCI Express lanes for GPUs and 24 threads of 4+ GHz rendering power (when overclocked) for just 400 Euros, which is objectively amazing. We have only AMD to thank for this after almost a decade of quadcore stagnation.
The results don't reflect the total system cost (GPUs need a host CPU, and both need a host motherboard etc.), only a first order approximation of the relative value proposition with some of the numbers available.
Without further ado, here are the raw numbers:
| Processor | Notes | Perf | Price | Value |
|---|---|---|---|---|
| AMD Threadripper 2990WX | 32c / 64t, overclocked | 9.833 | 1812 | 5.4 |
| AMD Threadripper 2950X | 16c / 32t | 6.593 | 893 | 7.3 |
| AMD Threadripper 1920X | 12c / 24t | 5.006 | 400 | 12.5 |
| Nvidia GTX 2080 Ti | 11 GB memory | 38.3 | 1200 | 31.9 |
| Nvidia GTX 1080 Ti | 11 GB memory, overclocked | 26.072 | 690 | 37.7 |
| Nvidia GTX 1070 | 8 GB memory | 17.37 | 430 | 40.3 |
From these results we can see, GPUs offer a great value proposition if you can fit your scene in 8-11 GB of memory and unidirectional path tracing renders the scene efficiently. The recent discount on the Threadripper 1920X makes it extremely attractive on its own, as well as the basis for a multi-GPU system due to its large number of PCI Express lanes; for a little more money you get full utilisation of the silicon and higher stock clocks in the 2950X, which also maximises high-powered rendering value for CPU bidirectional path tracing.
Prices were sourced from Geizhals, and benchmark results from TechReport, Phoronix and the IndigoBench database. Please note, this post is my personal opinion and not endorsed or sponsored by anyone.