Next gen Display port 1.5 will allow 8KX to use one cable, but still no GPU will run it (a card twice as powerful as the 2080ti or 2080ti SLI for 80hz), so 8K+ should be offered as well

Pimax Hardware P2: 8kX
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Providing there is a 4k screen which can refresh to 90hz then we can have the same specs as the 5k+ on an 8KX if theres a gpu which can run it in the next few years and better screens.

"… bandwidth of around 64.8 Gbit/s for the next version of DisplayPort. Assuming 8b/10b encoding, this would give a data rate of 51.84 Gbit/s.

This should allow for uncompressed RGB / YCBCR 4:4:4 video formats as high as:

  • 8K (7680 × 4320) @ 60 Hz 8 bpc (24 bit/px) or 50 Hz 10 bpc (30 bit/px)
  • 5K (5120 × 2880) @ 120 Hz 8 bpc or 100 Hz 10 bpc
  • 4K (3840 × 2160) @ 200 Hz 8 bpc or 180 Hz 10 bpc

Higher resolutions/refresh rates should also be possible through the use of DSC (compression) or chroma subsampling (YCBCR 4:2:2 or 4:2:0). Higher uncompressed formats may also be possible if the new version replaces 8b/10b encoding with a more efficient encoding method."

DP 1.5 Cable bandwith limit @ 10 bpc
4k : 3840 × 2160 = 8,294,400 pixels x 180(180hz) = 1,492,992,000 pixels p/s.
5k : 5120 × 2880 = 14,745,600 x 100(100hz) = 1,474,560,000 pixels p/s

Pimax 5k+ required pixel throughput for 90hz (2080ti required for modern rasterized titles)
2560 x 1440 x 2 = 7,372,800 x 90(90hz) = 663,552,000 pixels per second

Pimax 8KX required pixel throughput for 90hz
3840 × 2160 x 2 = 16,588,800 x 90(90hz) = 1,492,992,000 pixels p/s

Pimax 8KX required pixel throughput for 80hz
3840 × 2160 x2 = 16,588,800 x 80(80hz) = 1,327,104,000 pixels p/s

it’s x2 the performance of the 2080ti required to run the 8KX at 80hz in current rasterised titles with the same performance as the 5k+ at 90hz on the 2080ti.

if the 2080ti in SLI gave you 200% stacking gains in performance in all titles, then you could say you can run the 8KX with a SLI setup with the same performance as 5k+ with a single 2080ti.

@Sean.Huang @Matthew.Xu @deletedpimaxrep1 @anon74848233 @Pimax-Support @PimaxVR
8K+ is more feasible of a product than the 8KX when the new 4k full rgb strip screens are available. We simply don’t have the raw GPU power to run the 8KX at 80hz, 60hz is even questionable as my mathematics project a 40hz maximum framerate on the 8KX with a 2080ti in current titles.

But looks like DP 1.5 will be able to provide x2 uncompressed 4k signals with no compromise to colour either. (8bpc gives 256 shades of colour for each pixel vs 1024 shades of colour per pixel for 10bpc)

…insane to think every second of playing on pimax 8KX at 90hz is one and a half trillion pixels generated and 16 million pixels per frame, but even the best gpu to date struggles to deliver a third of that (663 mill/s 7m/frame)… we need over twice the best gpu power that’s commercially available to consumers to run the 8KX using rasterized graphics.

Ray tracing performance
To put things in perspective, real-time ray traced scenes (which actually only ray trace the reflections and shadows in this demo and is a mix of rasterization and ray tracing) at 4k resolution - the 1080ti get 5fps and the 2080ti gets 30fps at 4k.

RTX is still at least 2-3 generations away from semi-ray traced environments being VR capable, as there needs to be x6 more RTX power to reach the 180 average fps required for 90hz @ 4k
for the 5k+ though, 50fps at 1440p in this demo indicates x3.5 more RTX performance than the 2080ti is needed for real-time semi-ray traced scenes at 1440p x2 at 90hz in VR.

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This will likely roll out with pcix v4.0 & the new amd cards possibly.

Amd is looking to be in the lead on potenial taking the lead.

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Theres not much point if no GPU has DP 1.5 and none have said they will use DP 1.5 yet.

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one peice of the puzzle is looking to be solid for the technology to be feasible, all we need now is better gpus and screens.

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Unless they have something like a linkbox that can accept 2xdp 1.4 input and convert, this won’t really be useful when no other current GPU will work.

As pimax use a propitiatory cable for the 5k+/8k there’s no reason why it won’t still be 1 cable to the HMD anyway, and split out to 1xUSB and 2xDP at the end, just as the current is split out to USB/1xDP

Note they have said they are aiming for 80hz not 90hz for the 8K-X.

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That’s an indication Pimax are planning to use the same pentile screen that the 8K is using for the 8KX, because the screen the 8K uses has issues maintaining a 90hz refresh rate and maxes at 80hz when overclocked.

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Maybe, although the discussion has been more focused on the scaler being the most likely cause for not hitting 90hz. Pimax have also said they are trying different screens so no guarantee its the same as the 8K at this stage. Maybe they decided as 80hz works and has become accepted its less of a headache trying to push screens to 90 that aren’t originally designed for it.

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Pretty sure I recall pimax devs saying that the reason 90hz wasn’t possible on the 8k was because of the failure rate of their 4k screens being overclocked to 90hz was too high, so they tried lowering it to 85hz and then 80hz to get a good enough yield.

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Never heard that it was a yield issue they have just talked about instability which meant they had to spend much time to get the 8k running during meetups. It has even been confirmed that a new scaler is coming that will have a higher bandwidth

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Yes thats that I meant, i was actually referring to the instability of the screens affecting the end total yield of acceptable consumer grade 8k units, as not enough units were reaching 90hz to have a high enough yield with the screens they were using so they had to lower the refresh rate to 80hz.

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Indeed pcix v4.0 has been mentioned by Amd. Dp1.5 only just mentioned specs. But when rolled out could be interesting for a variety of reasons & how it will affect Vrlink.

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It would also likely mean new Bridge chips needed as well.

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No it’s beleived to be an issue likely with the upscaler as another project is using the 4k panels at 90hz. These screens were first identified as pentile like in the First Tested Review.

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VR is going to need either software-independent and hardware intergrated foveated rendering (which is going to be tricky but could be implemented with gpu intergration by an eye tracking module sending a signal to the gpu pre-render so that the gpu knows what to render in what quality before the information and frame renders leave the gpu)

or a VRlink/NVlink with consecutive gains and not minimal gains by stacking gpus to achieve the acceptable performance required for higher grade resolutions (5K or 4K x2 VR at 90hz in the future)

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80hz makes sense as current top tier gpus only target 4k gaming. Mgpu is going to be necessary to drive the quality.

Amd infinity fabric gpus could be very interesting. Gpu multicore. As @D3Pixel mentioned.

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No they never said that; I know of. They did say I think it was Nordic already has a project running them stable at 90hz.

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Personally I think as you said independent equipment. Meaning putting stronger processors in the hmd to help boost & reduce load.

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that doesn’t make any sense to hobble the product just based off some other component they have no control over, pimax said the limitation was the upscaler used in the 8K and everyone believed them and assumed therefore the 8K-X would be 90hz… if the 8k-X is targetting 80hz then it most likely means it IS the panels problem, not the display driver, there aren’t any “processors” in the hmd, it already has double the number of display drivers compared with the 8K which should be complete overkill for bandwidth

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Yes but this theoretical performance gain will only apply in future games made with software which is coded to take advantage of multiple cores/multithreaded performance.

As far as DX9-DX-11 games which the 1080ti and 2080ti are still struggling to achieve 90hz average on most even older titles, those games are coded to only take advantage of single core performance and usually only 1-2 cores.

Considering that the current gen top tier gpus can barely push an acceptable average refresh rate at 5k+ resolutions, and that in the future we’ll be progressing towards chiplet designs with more cores in AMD’s next offerings and more RTX based infrastructure in future nvidia gpus,

This leads me to believe that future generation GPUs will actually be worse at performing at older games, due to RTX infrastructure not translating well to rasterized graphics and multicore chiplet gpu designs being hampered in single core performance and programs which only take advantage of 1-2 cores (old games, skyrim etc.)

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displayport 1.4 with dcs support can handle 8k 60hz compressed so really should be able to handle the 8kx’ 2*4k@90 on a single cable. pascal cards and later supports 1.4 (may need firmware upgrade) so unless the visually lossless compression kills the visuals there’s really no need to dual cables.