Is VR mostly GPU dependant?

[DeadlyPilot]

I posted a similar question earlier but I believe it needs some rewording. What kind of workload does VR add to both the CPU and GPU? If it adds more to the GPU than CPU, then I would imagine that I could get away with a slower CPU than I would be able to in non VR applications. Basically I'm asking weather or not VR will move bottlenecks from the CPU to the GPU?

[Orangeator]

Normally games are more GPU dependent however, when it comes to higher refresh rates and minimums (both things that are important to VR) the CPU becomes a lot more important.

[DeadlyPilot]

Just now, Orangeator said:

Normally games are more GPU dependent however, when it comes to higher refresh rates and minimums (both things that are important to VR) the CPU becomes a lot more important.

My understanding is that VR renders the game's environment at one frame rate, and the head tracking at another frame rate. So basically whatever frame rate you are getting, it gets re projected to 90fps. Which is a high frame rate, but the games environment is still rendering at a lower frame rate. So wouldn't this mean its more on the GPU side?

[Princess Luna]

 

Running good VR is basically run a 4k panel, you need something strong enough for it GPU wise and a GPU that powerful needs an equally good CPU so the rig remains balanced.

[KenjiUmino]

7 minutes ago, DeadlyPilot said:

I would imagine that I could get away with a slower CPU than I would be able to in non VR applications.

nope ... that is not how it works.

 

VR does not "move" workloads from one component to the other - if anything it adds more load.

 

so if anything we are talking about how much extra load to expect on CPU and GPU

 

from what i know, there is more extra load added to the GPU

[DeadlyPilot]

Just now, KenjiUmino said:

nope ... that is not how it works.

 

VR does not "move" workloads from one component to the other - if anything it adds more load.

 

so if anything we are talking about how much extra load to expect on CPU and GPU

 

from what i know, there is more extra load added to the GPU

Never said it "moves" workload. If more workload is given to the GPU than the CPU, the CPU then has more time to finish its job, meaning the CPU will be waiting around for the GPU to finish. This is what introduces bottlenecks.

[DeadlyPilot]

6 minutes ago, Princess Cadence said:

 

Running good VR is basically run a 4k panel, you need something strong enough for it GPU wise and a GPU that powerful needs an equally good CPU so the rig remains balanced.

Well, running 4k will bottleneck the GPU much further than running 1080p. Because your giving the GPU more to render, while the CPUs job remains the same, it gives the CPU more time to finish each frame. So I would imagine a better CPU isnt needed for VR

[DeadlyPilot]

Anyone?

[Mira Yurizaki]

My first thought was it should increase the CPU workload by some factor, because you need to send two different render commands to the GPU for two different view ports.

 

But then I remembered render to texture is basically the same thing and has been a staple feature in game engines since Source. So... probably not really that much more work.

[ARikozuM]

VR requires more GPU horsepower as you're taking a two views and combining them for a convincing 3D effect. Most VR games that I've played haven't need much from my i5, but they do tax the 970 and 1080 in my system. I haven't tested whether a Pentium or i3 can provide a good experience, but each GPU manufacturer has come out with techs that can help VR (green has SMP so that two views can be used for more accurate 3D and I forgot what AMD calls it, but it fakes frames by approximating between the old frames and movement of the headset). 

[Marinatall_Ironside]

3 minutes ago, ARikozuM said:

(green has SMP so that two views can be used for more accurate 3D and I forgot what AMD calls it, but it fakes frames by approximating between the old frames and movement of the headset)

Simultaneous Multi-Projection is Nvidia's solution to improve not only the performance in VR applications, but to also improve the accuracy of Surround displays by rendering a game (or image) in 16 viewports. This Techquickie video gives the full context of how SMP works.

 

[DeadlyPilot]

 

3 minutes ago, ARikozuM said:

VR requires more GPU horsepower as you're taking a two views and combining them for a convincing 3D effect. Most VR games that I've played haven't need much from my i5, but they do tax the 970 and 1080 in my system. I haven't tested whether a Pentium or i3 can provide a good experience, but each GPU manufacturer has come out with techs that can help VR (green has SMP so that two views can be used for more accurate 3D and I forgot what AMD calls it, but it fakes frames by approximating between the old frames and movement of the headset). 

Makes sense, so i can probably get away with a 3770 w/ a 1070/980ti I'm sure. Also, are Polaris and Pascal really that much better than say Maxwell all else being equal? I want to know if a 980ti would be as good as a 1070 in vr.

 

Also, are the games rendered in 360 degrees regardless of where the person is looking?

[ARikozuM]

16 hours ago, DeadlyPilot said:

Makes sense, so i can probably get away with a 3770 w/ a 1070/980ti I'm sure. Also, are Polaris and Pascal really that much better than say Maxwell all else being equal? I want to know if a 980ti would be as good as a 1070 in vr.

Pascal introduced SMP. I don't know if Nvidia would have added it to Maxwell cards. Either way, you should have no trouble running VR with those cards. 

16 hours ago, DeadlyPilot said:

Also, are the games rendered in 360 degrees regardless of where the person is looking?

That I wouldn't know. There would be an advantage in latency of the drawn space as it is already rendered, but the intensity may not match every GPU for VR.