80hz. Finite bandwidth. No reason software can’t mediate resolution for more hertz


As someone who’s worked with hardware for years dealing with av gear, I’ve never seen ONE piece of hardware that didn’t offer options for its max bandwidth budget.
If pimax can’t push 80hz further due to the quality of the circuitry and design of it in the bridge chip, at least give us the option to run at high frequency in software for less resolution. You could even do this per game, as some games might require faster display times than others.
So as an example, watching 4k per eye native might be possible at 30hz for say, movies or doing windows desktop things.
And then lower it substantially and use super sampling instead as we currently do for other games like skyrim.
What is the max refresh rate of the displays isolated? Maybe it’s something higher than 90hz? Or the upscaler, could this also be true? Anyway, that’s a different discussion.
Software can mediate the bandwidth balance between hz and resolution. The bandwidth cap doesn’t discriminate on a digital signal. Data is data.


Mixed reality fix 2 spec of computer for run 60Hz and 90Hz, but from new update, user can choose manually for “auto”, “60Hz” or “90Hz” by themself.


Indeed though it might still be an issue of the bridge not being able to be stable at 90hz itself. It might be an issue of Peak value opposed to remaining steady at 90hz.

Hopefully @xunshu can enlighten us with if they have done any testing at 1080p per eye at 90hz.

@lonetech & i believe @brian91292 had offered some methods of reducing bandwidth in the bandwidth summit discussion. But we never heard if the team explored those ideas presented or not.


I would gladly use two cards with one hdmi for each eye if that’s what it meant for it to work. Hopefully that is one path they are looking at.


Thats the 8KX as far as i know


Yep though all models now use DP.


What, chroma subsampling? It’s how I managed to play left 4 dead 2 on 4k 60fps back in 2012 on a 1.4 hdmi pcie chip.
I don’t really know what peak value means but in general terms the peak value of a lower resolution @ 90hz would be substantially less data throughput than what they’re currently aiming for. Same with 4k@30hz which would be cool for movie viewing where maybe it looks the screen in front of your eyes or something.
But just to reiterate what @xunshu mentioned I believe at one point, is that there was flaws with emf protection and interference at the amount of voltage I’d assume they were attempting to widen the bandwidth pipe. And also other factors like sending the signal on 10 meter cables required more power.
I’m not sure how likely it is they are working with the bridge chip manufacturers because I have heard that they (the bridge chip people) had been advertising the chip with a claim of a certain bandwidth that the chip just doesn’t seem to handle.
The other more obvious way that probably affects us more is mediating the problem through software. Perhaps using a lower bit depth of color which probably would look not as good. They certainly could add a second bridge chip in there and run dual display port to the hmd, but I guess that would just be the 8kx, no? It kind of seems like all the backer units, in fairness, should have the extra bridge chip, unify the product in the process. Functionally they will have 5000 happy reviewers, good press for delivering the product they promised in media, and better sales going forward.


Peak as like Audio. Peak watts for example in a speaker at 100watts can do 100watts but only for short burts.

Rms in audio is peak b4 distortion (usually something like 60% of peak value)

But yeah is a bit of a mess. Gigabyte states on their site theorectical performance of graphic cards based on all componets in the card working ideally; more or less.


Audio signals are an analog format and it’s not the same fortunately. However when in comes to the mineral type and quality used in components it does have a profound effect on digital data throughout.


The bridge chip for the base 8k is cqpable of 4k 50hz in stereo 3D. There is no reason that Pimax cannot have a 4k 45hz mode that is then reprojected to 90hz in the hmd.

You could also do native 3440x1440 @60hz and have that reprojected to 90hz

Even 4k 60hz is doable with 4:2:0 chroma subsampling.

I dont think we have any reason to worry. Options will come. Right now, I just want to see it working and see it shipped at descent quality.


Even without on-HMD reprojection, they should certainly be able to reduce horizontal resolution on the last 50 degrees FOV of the transferred image, or use even more such… ehm… “lens-matching zones”, to optimise not only bandwidth use, but potentially better utilise the native resolution of the device in the centre of the image, too. That would require a little bit more complexity on part of the scaler, though.


This is a reasonable request from the consumer’s point of view. I’m supporting such request as a must have feature.
This is not necessary to achieve in this state of developing but definitely must be upgraded true software in the future after product come to market so this will not be time consuming and slowing down development in general.
I think it is reasonable and doable.


Proof of concept needed. No proof of concept, cannot detect unforeseen fundamental issues with implementation.


For the time you have been around this forum, have you read any explanation of the issue from Pimax? I have not, even though there were some deep technical discussions about the possible cause(s) in the past, Pimax never acknowledged or proved wrong any of it. The only statement they issued so far was - “it should have been working”.

If they are not able after 5 months to come up with a clear answer (of any kind), I would have to assume, from my experience with different SW and HW designs, that they do not understand their own design. In other words they are clueless and lost.

Someone who lacks fundamental knowledge of the deficiencies of its own design would be hardly qualified to implement what you are asking for. The question is not if it is possible, but if Pimax is capable of doing. You have your answer on this forum.


Without a doubt they have consultants addressing different problems.


Did the hdmi versions reach the 90hz or was the an expectation also


There are two theories:

  1. It did, but no one else from Pimax was able to demonstrate it.
  2. It did not and Pimax lied about it.

Unfortunately it is difficult to prove either one. If you are interested, google the video from Tested with Pimax CEO where they ask this question explicitly and the CEO explicitly answered. This was later explained here on forum by someone from Pimax that the headset with HDMI was able to reach 90Hz refresh however with some hiccups (which were possibly observer by Tested - this is my interpretation)

Everyone else who was able to review the unit either with HDMI or DP was not able/allowed to make a measurement and only anecdotal reference about “bad tracking” was in Linus review, which however was bad in its own form, so also not really representative.


If they do, they are apparently of no use either.


Maybe new talent needed?


Was the version running off two hdmi at 90hz?