Can we establish the real facts about PC hardware for VR?

Hi, VR devs!

As a PC hardware enthusiast, I'm trying to ensure that my PC is optimally powered for VR, and I'm in a position where I give build advice to large numbers of other PC gamers, many of whom want their PCs to be ready for Oculus CV1. Because I'm in this position, I've been getting into lots of debates, mainly related to the Oculus minimum hardware specs and the likelihood of multi-GPU support in the near future. I've spent a lot of time talking to fellow gamers, when really I should be talking to actual developers. In that spirit, I hope that my questions are welcome on this forum. Please let me know if I should post this elsewhere. Trust me when I say that if you can help me settle this debate, you will be helping many other PC gamers as a result.

I'd like to focus this thread on the minimum specs quoted by Oculus: a GTX 970 (or R9 290) and an i5-4590.

Just looking at the numbers, the raw graphical power you need to display game images on a CV1 screen is enormous. Taking into account the 1.4x 'eye buffer' on the 2160x1200 resolution, you get a true rendering resolution of 3024x1680 for a VR headset. (Correct me if I'm wrong about the eye buffer -- I assume Oculus and Vive are the same, and I know Vive has a 1.4x render resolution.)

Trying to target 90 FPS/Hz at 3024x1680 requires roughly 90% as much graphical power as rendering 4K (3840x2160) at 60 FPS/Hz. As Oculus have said themselves, it's also more than 3 times the graphical power required to display a game at 1080p at 60 FPS/Hz.

As everyone probably knows, rendering modern games at 60 FPS with 4K resolution requires a huge amount of graphical power. Looking at a modern PC game like Fallout 4, even a GTX 980 Ti averages only 46 FPS at 4K on Ultra settings. That would translate into about 77 FPS on an Oculus. A GTX 970 averages 33 FPS in Fallout 4 at 4K. That's about 55 FPS on an Oculus, assuming it's directly translatable.

If Fallout 4 were to have launched with VR support, you would need a much more powerful GPU than a GTX 970 in order to play it at 90 FPS on the Oculus. In fact, you'd probably need a multi-GPU system, but from my understanding, multi-GPU support for VR is still under development. (It seems to me that multi-GPU support will absolutely need to work for AAA gaming at 90 FPS to happen.)

My concern is that many gamers are going to be building PCs with GTX 970s on the promise that it will run games at 90 FPS. But based on the math, many new AAA games will need much more power than a GTX 970 to run at high framerates.

When debating this, some people have told me that games designed specifically for Oculus will indeed run at 90 FPS on a GTX 970 because that's the hardware that the developers are targeting. I hope they are right, but I'm still skeptical. You cannot escape the fact that you're trying to pump out 457 million pixels per second (3024x1680x90). Based on my knowledge, a GTX 970 simply cannot perform at that level unless the game is only moderately intensive on graphics. You sacrifice looks, or you sacrifice framerates.

A flagship VR game like EVE Valkyrie looks just as visually impressive as Fallout 4, if not more so. I'll be extremely impressed if gamers are able to achieve 90 FPS with a GTX 970 without significantly dialing down the visual quality of the game. I really, really hope they're able to. But I'm going to remain skeptical until I see it happen.

I imagine two broad classes of games that will be released with VR support:

1. AAA games with really high-end graphics. These will have the resources to optimize for a variety of PC configurations, and will support SLI/CrossFire, because that will be the only way to experience the games at their full potential. These games will require much more graphical power than a GTX 970 can provide.

2. Less expensive games where the focus is on gameplay or story rather than graphics. These games will be less graphically demanding, so it won't matter if they support SLI at all, because even a GTX 970 will be more than enough.

My concern, once again, is that many first-generation adopters are building PCs with a GTX 970 (as suggested) and anticipating that they'll be running the flashiest games at 90 FPS when their Oculus comes out. That's certainly the perception that I see in discussions among the general gaming population.

Can someone shed light on this concern? Am I completely off-base, or will the first generation of games designed specifically for Oculus just have to look very simple graphically compared to today's modern PC games if we want to run them on 970s?