Gsync/ freesync in VR headset displays?

[wunkley]

Total VR noob with a really basic question - do the current crop of VR headets support gsync/ freesync or the equivalent technology?

If not, as most seem to be 90Hz displays - is it the case that if you can't hit 90fps constantly in a game then you get hitching/ judder if the frame rate drops under that, the same as you do on a normal monitor without gsync/ freesync?

I've been gaming on a Gsync monitor for the last 4 years, and can never, ever go back to any sort of hitching/ judder/ stutter that you get in games, if the frame rate can't match the Hz of the display. I would guess stutters would be even more noticeable and horrific in a VR display too?

 

[wunkley]

Thanks for the good answer bud, much appreciated.
My main use for a VR headset would be for sims like flight sim 2020, DCS world etc. I'm just worried what the VR experience will be like for a smoothness Gsync junkie like myself.

As mentioned stutter / hitching is just the worst thing for me now and I can't play games without Gsync unless they can lock to at least 60fps (eg on my 60Hz OLED).

Flightsim 2020 at best can hit 60fps for me sometimes, but mostly is in the 40-50fps range. On a gsync monitor this is ok, but what is the experience like in a VR headset? Will there be judder/ stutter?

 

[wunkley]

A VR headset, like the G2 or Quest 2, is basically 2x 4k monitors. And generally it's felt that 72fps is the minimum you want to be hitting, with 90 being preferred, to avoid sickness. As above, 45 can be reprojected as 90, but if your machine is struggling on a single monitor, it may not be able to manage a headset.

I've got a 3090 so pretty well covered on the GPU front This is currently still paired with my, getting on a bit, 5930k (at 4.5Ghz) x99 rig. I'm waiting to upgrade CPU, etc when I feel I really need to. Not found the need yet.

I naively didn't realise the specs for VR were per eye, so almost getting on for driving x2 4k monitors with the latest headsets like you say. That's insane. What games can run at that high a res - at 90FPS!? Even on a 3090?

P.S. The newish Reverb G2 is the one I'm looking at. I'd try the Quest 2 in a shot given the price and the fact that I've never used a VR headset before, but, the fact it's totally tied in to Facebook means I won't use it. I loathe Facebook.

 

[wunkley]

MSFS performance in VR is very poor currently. You'd be looking at 30fps on a G2 and 3090... by dialling down settings and resolution as low as one could bear, I can get to 45-50fps and my 5800X starts to become limiting but the performance is so variable (and IQ so comparatively low) you can't really stick it to 45fps so need to drop down to 30 as the next direct division of 90. I find it ok personally, but if you are particularly sensitive to judder or low framerates you will struggle. There is the option in OpenXR to reproject from 30fps (so two interpolated frames to one real one) which makes things smooth but also introduces some blurriness and artefacting that I don't enjoy. My personal preference is motion smoothing off, 30fps and locked in the Nvidia control panel to that.

The Reverb G2 is 2160x2160 per eye, but due to the way VR rendering works you ideally would render at a little over 3000x3000 per eye (the 100% setting in steam and OpenXR) so really you are pushing two 3000x3000 monitors (~9 million pixels per eye vs ~8.3 million for a single 4k screen) at 90hz. I can run a lot of my VR games at 90FPS and 100%, some more demanding games like the modern sims I have to dial back to 70-80% resolution, and for some like DCS I can stay at 100% but have to accept 45fps with reprojection but it works very well in that game imo and DCS + Reverb G2 + 3090 is an awesome experience.

Thanks flyboy, lots to ponder. Do you have the G2 and a 3090 then?

Just wondering as it's my first foray into VR if I should suck up the Facebook requirement (just make a fake account?) and get the Quest 2. It seems cheap as chips relatively for the specs you get.

Looks like the G2 is in stock direct from the HP site for £658. Quest 2 in stock many places for only £299 (£324 with a cable to tether to PC).

What would you recommend for a VR virgin?

 

[wunkley]

Yup. G2, 5800X and 3090.

Ignoring the Facebook issue as that’s personal, the Q2 is a better all rounder headset, especially after a few upgrades/mods. Don’t set up a fake account btw as they may ban you and you could lose anything you’ve purchased in the store. Just set it up correctly, lock down all the privacy options and don’t bother using it for anything.

If all that really interests you about VR is seated gaming, then the G2 is superior in most ways. It’s more comfortable as standard, much better audio, higher sharpness (in the centre at least) and better picture quality, better IPD adjustability too.

For pretty much everything else the Q2 is arguably better IMO. The ability to play standing/room scale wire free both with standalone VR games and using wifi tethering with Virtual Desktop really can’t be overstated. Tracking is better, controllers in general are better, oculus software is better and far more actively developed with new features than WMR. It is also infinitely more popular so more options regarding accessories and of course you get access to games exclusive to the oculus PC and mobile platform while also getting access to all the rest anyway through steam and OpenXR.

Thanks bud. Gaaah this is getting confusing. I'm only really interested in 'sat at the PC' type gaming, I think anyway. That could have course change.

I'm also looking at the older Rift S now. Can get that for even cheaper and although it's resolution is much lower then the Quest 2 it's a direct display port connection and doesn't need occulus link - some think the compression of this makes the image a bit soft.
What would you buy VR wise if you had nothing yet and were buying something today? Still the G2?

 

[wunkley]

Hmmm. Looking at some comparison 'through the lens' videos on youtube. The G2 does look much better. Not just the resolution and clarity but black levels, contrast and colour quality is much better and the Quest 2 can have colour banding due to the compression. I'm a graphics whore. And that ******* facebook requirement, never mind VR making you feel sick, have you seen Mark Zuck the Borg's face? I don't think I can stomach having to be part of bookface.

 

[wunkley]

I've ordered a G2 The overall resolution/ clarity + superior black levels (this a biggie for me!), contrast and colour have swung it. I'm a graphics whore. The Quest 2 seems amazing value but I'm of the mindset buy 'big' or you just end up buying twice - which ultimately costs more. And i know I keep saying it, but **** Facebook. Seriously, I'm a principled SOB and I can't justify giving them a penny, or any 'data'.

Sounds like the G2 has been hard to get (not as bad as GPUs!) but was available to order on the HP website today showing "48 hours delivery" - It didn't say in stock explicitly but I assume 48 hours delivery means it is in stock???

Also, I've realised/ worked out that the overall resolution of the G2 is nothing like running "x2 4k monitors" like someone earlier posted. The overall resolution that the GPU will have to drive is:

2160 x 2160 x 2 = 9,331,200 pixels

UHD/"4k" (not really 4k as we know) is 3840x2160 = 8,294,400 pixels

So, unless I'm missing something (which is possible as I'm a VR virgin) the G2 is not significantly harder to drive than standard UHD/4k, and a 3090 should easily do the job, no?

 

[wunkley]

The main difference is 4K 2D games don't run at 90hz, wheras VR games normally do, and if there are any major frame drops in 4K 2D games they don't make you physically ill, unlike in VR where it can cause a form of motion sickness.

But a 3090 is the best card right now for running the G2. Just don't expect to max every game, as some games are either demanding or poorly optimised for VR, and the G2's resolution is very demanding in VR.

thanks bud. Yeah, I get that 4K beyond 60fps is a tough call at max settings even for the 3090. I have no problem turning down a few settings to get a balanced optimized frame rate.

Anyone know how VR feels at half refresh rate? Is that not a thing? Is a locked 45 FPS ok in VR or is it just vomit inducing? 45 FPS on my gsync ultra wide in flight sim 2020 is perfectly playable to me. Is anything under 90hz 90fps just a no no for vr?

 

[wunkley]

Nope. VR headsets aren’t monitors, you have a lens between you and the screen which creates distortion...

Like I said above the headset is designed to work with a render resolution of over 3000x3000 per eye... that’s ~9 million pixels each or 18 million total vs 8.3 million of a 4k screen.

In a really quick high level explanation - in order to have an image look correct after it has passed through the lens it needs to be pre-distorted (called barrel distortion as the end result looks barrel shaped). Since there is currently no mainstream rendering pipeline that outputs a predistorted image, you have to render the scene traditionally to a buffer. That image is then subjected to barrel distortion which involves stretching and enlarging the image. That process requires you to render at a higher resolution otherwise you will end up sub sampling the parts of the image that are being stretched.

Forget what you know about panel resolutions from flatscreen. There is no “native” resolution for VR with current pipelines, if you set 2160x2160 per eye then you are subsampling the entire frame after distortion is applied and clarity suffers significantly. The “optimal” setting is enough that you get a roughly 1:1 rendered to displayed pixel in the most distorted area of the image, so gives the best image quality but still isn’t “native” as you are supersampling all the less distorted areas of the image. On the G2 that optimal setting is a little over 1.4x panel resolution (changes per subpixel, but technically it would require on average around 1.5x to get every last pixel at least 1:1). That is what steam will set as the 100% target for the G2. I forget exactly but it’s something like 3160x3072 per eye.

It’s not quite as straight forward a comparison as that as you can use hidden area masking to reduce (but not eliminate) render load for areas that will be off the screen anyway after distortion which helps a little, but start including that and it gets pretty confusing pretty fast. Then there are certain other technologies that can complicate direct comparisons further like Nvidia’s SMS or the upcoming sampler feedback in DX12U. As a basis for general comparison it’s close enough though - point is you can’t necessarily precisely compare the 18 million vs 8.3 million numbers.

You can run lower render resolution by setting less than 100% resolution but you aren’t then getting what the headset is capable of. Anything less than about 75-80% becomes very noticeable to me in terms of clarity fall off. Between 80-100 it’s still noticeable for me but more subtle. Above 100 you just get improvements to aliasing really rather than more detail.



As mentioned the normal course of action for a game that you can't get to run consistently at 90fps would be to use motion vector reprojection to go from 45fps to 90fps in the headset. To work most effectively it does require some headroom, so you'd ideally be able to hit a minimum of 60fps with it disabled and then it'll give you a solid 90fps and do a pretty damn good job in most games of giving you good quality interpolated frames.

Anything else, totally depends on the individual. As mentioned I lock to 30fps with no motion smoothing in MSFS and while I'd like it to be faster it doesn't cause me any sickness... but I've never suffered VR sickness anyway. Others might find that very uncomfortable. If you are going that route of sub 90fps but no motion vector smoothing then it's important to lock the framerate to a sub division of 90 - ie 45 or 30. At 30fps I get each frame displaying for 3 refreshes, so while it's crap (especially looking out the side window) it is at least consistent. If I uncapped with my current settings I'd get around 35fps which would result in some frames displaying for 3 refreshes and some frames displaying for 2, which leads to a much more stuttery result despite the higher FPS.

Cheers flyboy. That makes a lot of sense. I’m familiar with a lot of the principles you talk about there, Just the specifics of VR are all new to me so it’s interesting and a bit of a learning curve.
You really seem to know your onions when it comes to VR, I could be tapping you for more info hope that’s ok!?

I’m a bit trepidatious now about ordering the G2. It feels like even the 3090 is a long long way off from running a VR experience as it should be with such a high res display. Thinking now I might cancel and go for a used Rift S maybe? Much less demanding resolution. Thing is, I see no point going half arsed into VR. I game at 4K, hdr with ray tracing now. If I’m going VR I want the fidelity to be worth it, otherwise I won’t use it I already know.

Given the sheer pixel count the G2 has to drive, how is any game playable at 90hz native, even on a 3090 - basically “Double 4K” at 90fps. You have to run games at basic low settings yes?

 

[wunkley]

Ok another separate question then I’ll call it a night....

DLSS. Total game changer for me since getting a 3090 ampere and experiencing it for the first time.
Seriously impressive tech that takes the burden off high res gaming with ray tracing. So, can this/ will this be used for VR games? It would makes the ultra ultra high res of the G2 much more attainable at the high frame rates needed for the best experience.

 

[wunkley]

Have you played any VR at all yet?

Don't go for the Rift S. There are three headsets out now worth buying, The Quest 2, Reverb G2, Valve Index.

This is my simple breakdown.

If you want the best black levels with the widest FOV and arguably the best controllers, get the Valve Index.

If you want the best clarity and highest resolution, get the Reverb G2. ( This is the probably the best choice if you are mainly playing Sim games)

If you want the best all rounder with the ability to play games anywhere, and PC games wirelessly. Get the Quest 2.

Since you mainly plan to play flight sims, the Reverb G2 is the best option. And, you have to stop comparing pancake games with VR games. I guess that's not fair as if you haven't tried VR, then you can't know what it's like.

Buy the Reverb G2, start flight sim, be amazed. It's the difference between watching a game on a screen compared to actually been in the game, sitting in the cockpit.

Not yet bud no. I strapped a first gen oculus on my face for some awful corporate ‘app’ about 5 years ago, but never gamed in VR no. Like the cartoon flyboy posted above, I’ve always been keen but waited until I thought the quality was good enough to dive in! I think that time is here now though, but it sounds like the pc hardware grunt required to get the best of it might be a gen or 2 behind, as is often the way.

And I ordered the G2 yesterday from HP, should come in the next few days. Lots to play with and I weirdly enjoy experimenting and fine tuning stuff to get the best performance, so I’ll probably spend more time fannying around with settings rather than gaming. Sad but true.

 

[wunkley]

One Gsync note. I turn Gsync and vsync off for my monitor in Nvidia control panel when doing VR stuff. 60hz monitor and 90hz headset. It may be something that doesn't affect all set ups but it used to cause me much weirdness before I worked out why it was happening. I do it out of habit now. Was never an issue with a 75hz monitor and 72hz headset.

That's something to think about. Is it worth disabling other monitors altogether when VR gaming? On a side note I run my main ultrawide gsync monitor at 90Hz anyway, so it may get along well with a 90Hz headset. I do however have a small 8 inch lcd monitor clamped to the side at 60Hz that I have all my HWinfo widgets stats running on though, so that might be an issue. Is it generally a known problem to have multiple monitors of different Hz connected along with a VR headset at the same time? Hope not...