As the days pass, we draw closer to a potentially seismic change in the PC gaming space - the arrival of Virtual Reality experiences, brought to life via the Oculus Rift and HTC's Vive. And for many, one key question needs to be comprehensively addressed - whether their existing gaming PCs can handle the strenuous requirements of the VR experience. And if they don't, what hardware will need an upgrade.
There's a sense that there's a lot of conflicting information out there. First up, let's take a look at the Oculus minimum spec:

  • Nvidia GeForce GTX 970/AMD Radeon R9 290 equivalent or greater
  • Intel Core i5 4590 equivalent or greater
  • 8GB+ RAM
  • 2x USB 3.0 port
  • HDMI 1.3 video output supporting a 297MHz clock via a direct output architecture
  • Windows 7 OS or greater

Some say that less than one per cent of the gaming PCs out there can meet this specification, but it's certainly a good place to start from Oculus, certainly bearing in mind the GPU spec. Take a look at Steam's hardware survey - probably our best look into the hardware being used by core gamers - and the GTX 970 absolutely dominates. Indeed, there have been some months where that specific GPU has accounted for over five per cent of all Steam users. Only Nvidia's older GTX 760 gets close.
"The recommended spec will stay constant over the lifetime of the Rift," says Oculus. "As the equivalent-performance hardware becomes less expensive, more users will have systems capable of the full Rift experience. Developers, in turn, can rely on Rift users having these modern machines, allowing them to optimise their game for a known target, simplifying development."
There's just one problem. To run the same game at full-spec VR, we are looking at a colossal increase in pixel-throughput. As Nvidia's general manager of Shield, gaming and VR business, Jason Paul explained in a VentureBeat interview:
Digital Foundry VR PC build tips

When the time comes, we'll be putting together a comprehensive build list for Virtual Reality gaming, but right now, the lack of available software - and indeed hardware - means that any recommended set-up is going to be speculative at best. However, based on our benchmarking experience on a range of traditional gaming titles, we can put forward some ideas on how component choice may impact a VR build.

  • USB 3.0: A lot of users trying theOculus Rift configuration tool havediscovered that their USB 3.0 throughput fails the test. We suspect that the firm's recommendation for the Haswell Core i5 as opposed to older, more popular chips may well be down to native USB 3.0 support in the surrounding architecture. To what extent this may actually be an issue, and whether it can be circumvented with an add-in USB 3.0 expansion card remains to be seen. HTC Vive's requirements here are also unknown right now.
  • Lowest frame-rate is the key benchmark: VR requires a 90fps minimum but more importantly, it requires consistency. Bear that in mind when looking at CPU or GPU reviews.
  • Core i7 beats Core i5: In our CPU-bound gaming benchmarks, we have observed that game engines using eight processing threads enjoy a performance boost on the Core i7 chips vs their i5 equivalents (even when overclocked). It seems that more threads has a particular impact on lowering stutter in CPU-bound scenarios, resulting in an improvement on lowest recorded frame-rates. This could help in a VR scenario, where sustaining 90fps at all costs is so important.
  • Nvidia's DX11 driver is faster: We expect GPU to be the major limiting factor in VR gaming, but if CPU is an issue, Nvidia's DX11 driver has proven to be significantly faster than its AMD equivalent, exhibiting less stutter at higher frame-rates. DX12 and its open equivalent Vulkan are the future though, and although we are lacking software to really put these new APIs through their paces, all indications suggest that both AMD software and hardware is in excellent shape here.
  • Faster RAM could help: Our recent tests with the Core i3 6100 and theCore i5 6500 have revealed that in CPU-bound gaming scenarios, faster RAM can make a difference, raising minimum frame-rates significantly on some titles. Be aware that faster RAM typically requires a more expensive Z87/Z97/Z170 motherboard to run at its maximum rated speed.

We'll stress again that these are just observations taken from our experiences in benchmarking RAM, graphics cards and CPUs on traditional PC games and until there's actual VR hardware available with retail software to test, the only real advice anyone can genuinely offer is: the faster, the better.

"If you look at your typical PC gaming experience, 90 per cent of the gamers out there play at 1080p. For a smooth experience you don't want to go below 30fps. Compare that to VR where the displays are about 2K, but you have to render closer to 3K, and you don't want to go below 90fps. It's about a sevenfold increase in raw performance to render for VR versus traditional PC gaming. You have to do that in less than 20 milliseconds from head rotation to what shows up on your display."