Thanks @wendell
The KVM has been posted express and insured. I will email the tracking details through.
My KVM has made it safely back to @wendell. I’m interested in seeing what he finds.
I’ve had the Neo G8 directly connected to my 3080Ti for a while now and found some interesting clock speed and power usage behaviour between the 120Hz and 240Hz refresh rates.
At 4K120 and below the memory clocks are around 100MHz and the card’s power usage is 30-40w:
At 4K240 though, the memory clocks up to full:
Probably not related to the KVM issue, but thought I’d mention it as Googling this I only found this link but no real detail.
I assume this is intended behaviour for driving a high refresh rate
Update on this. @wendell has received my KVM and tested it with his Neo G9 and it worked. The Neo G9 has just under a million less pixels so I guess that could be the reason it struggled with the Neo G8 but worked with the Neo G9 at 120/240Hz.
Neo G9 - 5120 x 1440 = 7,372,800
Neo G8 - 3840 × 2160 = 8,294,400
My replacement KVM has been tuned for FIBBR DisplayPort cables. so I have three more of them on the way from Amazon US; 2x 2m and 1x 1m cables.
I’m just waiting now for my replacement KVM to be shipped, or if it is shipped, for it to arrive. And for the additional FIBBR cables to arrive.
A big thanks to Wendell and team for helping me with this.
Fwiw i think the 1m fibbr csbles are bugged but 2m is probably ok.
Yep that is why I ordered the two 2m cables just in case my 1m cables are bugged too. Thanks Wendell.
I received the replacement KVM, and I’ve realised my FIBBR 1m cables as @wendell said are bugged, useless, junk.
Wendell sent me a video of the KVM working at 4K120 and 4K144 in 10 bit HDR with an LG monitor, on all inputs with FIBBR cables which I assume are the 2m ones? That proves the replacement KVM works.
Unfortunately for me either the Samsung Neo G8 (Firmware 1003.0) really doesn’t like the KVM, or the FIBBR cables I have are no good. I’m suspecting / hoping for the latter.
With the 1m FIBBR cables in place I was unable to drive 4K60 with 10 bit HDR without flickering and black screens. I tested on every input/output combination.
Attempting 4K120 or above resulted in the monitor lighting up, Windows detecting it at 120 or above, but it not actually displaying a picture, and then eventually it would go to sleep and Windows would no longer report it connected. The old KVM Windows wouldn’t even know the Neo G8 was connected so this is an improvement.
I then thought I’d test the FIBBR cables for a longer period of time in conjunction with the cheap USB switch I’ve been using to get by while the KVM was being RMA. Initially the FIBBR cables seemed stable but after a period of time even a single 1m FIBBR cable between my 3080Ti and the Neo G8 started playing up. I did the same with the second 1m FIBBR cable and it didn’t show snow, just blanked the screen every few minutes.
I have another 1m FIBBR cable meant to arrive today, but I’m thinking of just raising a return with Amazon US for all three. They are rated for 4K144 but can’t even work at that rate.
Hopefully the 2m FIBBR cables that should be arriving Monday with fair better, otherwise I’m not sure what I can do here.
I also tried the replacement KVM with my original Club 3D 1m cables and it was the same as before. Are any other Fibre Optic DP 1.4a cables out there known to be compatible with the Level1Techs KVM?
Maybe the Neo G8 is finicky and hard to drive with a KVM. @wendell if you ever get your hands on one to test, please let me know. Maybe it is a Samsung issue and a updated firmware fixes it if the 2m FIBBR cables do not.
Thanks again @wendell for all your help. I’m out of ideas now.
Have you checked to see if your gpu was one of the ones that has an actual firmware update?
Yeah I its pretty crazy.everything worked on both the samsung lg amd gigabyte displays here with similar refresh resolution and bandwidth spreads.
GPU is Aorus Master 3080Ti running the latest F2 BIOS and running this nVidia tool said no update required
https://nvidia.custhelp.com/app/answers/detail/a_id/5233/?linkId=100000076816300
I’ve tried each of the three DP on the video card, each of the input/output combinations on the KVM. Wish the Neo G8 had a second DP input I could test.
The 3rd 1m FIBBR cable arrived today, and yup faulty. Could not even maintain 4K60 HDR without blanking directly connected from my 3080Ti to the Neo G8. All the 1m FIBBR cables are going back now.
Hopefully the 2m FIBBR cables work, however I have a gut feeling now that the issue is with the Neo G8 itself. I hope not. Wait and see I guess
I found one other customer in the db with a g8 and the issue was with usb not display so maybe some monitor to monitor variation. This is very similar to the issues with the g9 (non neo) early on that led to me shelling out way, way too much money to debug the g9 (neo) and raising a ticket with samsung and they ultimately did roll fixes into 1008 after about 2 months. I got an early version of that fw which resolved almost all issues.
We’ll get there, one way or the other, by hammering at it continuously 
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Thanks Wendell, appreciate the help. Will post again once the 2M cables arrive. Fingers crossed that fixes it.
Amazon US accepted my return of the initial 2x 1m FIBBR cables I bought. Turned out I was a day over my return period window Australian time, but in the US I was still within. Yay for different time zones. I linked Amazon to this thread and they accepted without question.
Whats crazy is i got one too and had the same issue sobhsve been studying that
The folks with thr way lower quality club3d cables also have tells in the packaging that its apparently different than proper cables too. Fun times.
The 2m cables arrived a day early (yay), but… they did not work (boo)
Do you mean you got a fake FIBBR cable for the 1m ones? If so here is a photo of the packaging of the 2m ones that just arrived. The packaging for the 3x 1m ones (2 now returned) and 2x 2m ones looks identical except for saying 6.6ft instead of 3.3ft.
I tested the FIBBR cables individually between my 3080ti and the Neo G8 and they work perfectly fine at 30Hz, 120Hz, 240Hz, but not at 60Hz. That is strange. Both cables exhibit the same behaviour
Then when running them with the L1Techs KVM, 4K30 HDR works, 4K60 flickers as per the direct connect, and 4K240 with DSC and 4K120 do not even display.
That got me thinking, is it the Neo G8 that hates FIBBR cables at 60Hz, and the KVM at anything above 60Hz in 4K 10bit HDR? So my secondary Samsung monitor is a U32J590 and I know it can’t do HDR but it can do 10bit according to nVidia’s control panel so I connected one of the 2m FIBBR cables from my 3080Ti to the U32J590 and switched to 4K60 at 10 bit (but SDR still) and it works perfectly.
I’m still using that cable as I type this reply with no issues so it is not as if the cable itself has an issue with 60Hz.
I’m starting to think this is a Samsung problem. Any ideas @wendell as I’m out of them
So I found something interesting. My Aorus Master 3080Ti might be a part of the issue as well.
I had a Gigabyte RTX 3060 Gaming OC on order to replace the GTX 780 in my second PC. When I hooked that PC up to the KVM, it worked at 4K 240Hz HDR on all ports except the top PC4 input. Sometimes it did hesitate and take a bit of time to light up the Neo G8, but flicking between KVM inputs fixed that.
I then put the RTX 3060 in place of the 3080Ti and I’ll be damned, again 4K 240Hz HDR worked on all ports except the top PC4 input. The FIBBR cables at 4K60 with HDR were also no longer flickering.
Googling “3080 DisplayPort flickering” unearthed a whole heap of issues with people reporting problems from 3070 and higher cards. I tried the suggestions there of switching back to PCI-E 3.0, and turning off XMP but neither of these worked for me.
For some reason with the FIBBR 2m cables, my KVM can do 4K120 HDR on all ports except one with the Neo G8 with the 3060, but not the 3080Ti.
I re-ran the 3080Ti Firmware update from nVidia and it confirmed it was already applied
I checked with Gigabyte to see if there was a newer BIOS and no I am running the latest F2 BIOS (94.02.71.40.45)
TechPowerup has the older F1 BIOS but I’m hesitant to try to flash that
Is this a Gigabyte issue or a Samsung issue, or both, I’m not sure. I’m thinking of ordering a FIBBR HDMI cable for connecting the Neo G8 to my primary PC as I’m not sure what else I can do from here.
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I got a 2m FIBBR Quantum 8K HDMI 2.1 cable to put between the AORUS Master 3080Ti and the Neo G8 and it works as a work around.
For some reason with nVidia Control Panel identifies the Neo G8 as a HDTV but does allow me to select the PC 4K resolution, but only up to 120Hz.
Interestingly I found an issue with the Neo G8 on HDMI that if you enable 240Hz on the monitor OSD, the monitor is no longer detected as Gsync Compatible in the nVidia Control Panel. If you switch the monitor back to 120Hz on the OSD, the monitor shows up again as Gsync Compatible, but of course you can no longer select 240Hz refresh rate in Windows.
Not a big deal I guess as the 3080Ti will never be able to run 4K at 240Hz.
I’ve also noticed some issues on my secondary PC with the Gigabyte RTX 3060 Gaming OC card that is connected to the KVM and then to the Neo G8 using the FIBBR DP cables. Occasionally will flicker, however this is only a couple of times per day. Also occasionally switching back inputs on the KVM to the secondary PC the Neo G8 will fail to light up. I need to switch KVM inputs away, power cycle the Neo G8 and then switch back.
I think now the Aorus 3080Ti Master is a finicky card for DisplayPort and the Neo G8 is a finicky monitor in general. I have no hope that Gigabyte will update the firmware for the Aorus 3080Ti this late, so I can only hope that Samsung do with the Neo G8.
Hopefully my next GPU purchase works better with the Neo G8 and hopefully Samsung have fixed the firmware by then too.
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Just another update, I’m trying to get Gigabyte to fix my Aorus Master 3080Ti but not having much luck. I got a new 6900 XT pretty cheap (also a Gigabyte card) and switched that in, and what do you know 4K120 and 240 with HDR works with no issues directly to the Neo G8 via Display Port and through the KVM with the FIBBR cables.
So I have the following working / not working with the KVM at 4K HDR now:
- Aorus Master 3080Ti - source of all the trouble
- Mac Mini M1 (Moshi or Club 3D cable) - 4K 120 HDR is working and stable with the replacement KVM
- Old Aorus Xtreme 1080Ti - Only works to 4K60 8bit, probably age of the card
- Gigabyte 3060 Gaming OC - Works 4K120/240 in HDR direct to the monitor and via the KVM with FIBBR cables
- Aorus Master 6900XT - Works 4K120/240 in HDR direct to the monitor and via the KVM with FIBBR cables
The fact that the 3080Ti has trouble with FIBBR cables directly connected to the Neo G8 DP, and the flickering occurs there, and the various mentions online of RTX 3000 series DP 1.4 issue, I’d say now the card is at fault. Hopefully Gigabyte reads this thread and accepts the RMA and fixes my card.
The 6900XT is nice, but HDR on the 3080Ti is much better.
google nvidia displayport firmware update, and apply that, bet it fixes it.
it’s possible that the dp is not training to the right levels properly on the 3080ti. the phy has something like 4 discreet levels iirc; it is usually a problem on a specific port and weird that all the dp ports won’t train to spec, though.
Is this the update? I’ve already applied that but no luck - NVIDIA Graphics Firmware Update Tool for DisplayPort 1.3 and 1.4 Displays
Yep it is all 3 DisplayPorts on the card exhibit the same behaviour. Googling 3080 Display Port flicker turned up some interesting videos which are similar to what I’m experiencing. Here is an example of someone else seeing something similar.
His fix was to reduce from DP 1.4 to DP 1.2. On the Neo G8 that is a waste.
I’m starting to think that some 3000 series cards have display port issues. My 3080Ti definitely does however my 3060 works flawlessly, and so does that 6900XT in testing so far. The 6900XT’s HDR is quite a bit duller than my nVidia cards though which is a shame.
The Mac Mini was an interesting case. On my original KVM I could not even select above 60Hz, it didn’t even show, and I could not turn on HDR either. With the replacement KVM @wendell sent, 4K works at 120Hz with HDR with both the Club 3D and Moshi cable.
@wendell and team, thank you so much for sorting out the KVM for me.
Hopefully Gigabyte come to the table to diagnose/fix my 3080Ti. I’m not having much luck with them to date. If anyone has a contact at Gigabyte please PM me.
Hey All,
Just wanted to add to the discussion and mention that I am unable to get the Level1techs 4-port/2 monitor DP KVM working with the Samsung 28" Neo G70A Monitor (LS28AG700) and my Gigabyte RTX 4090 Gaming OC card at 4K/144hz output.
I’ve tried both standard off the shelf cables, as well as the recommended FIBBR Fiber Optic 3.3" cables between the monitor and KVM, and 6.6" FIBBR fiber cables between the KVM and the PC, but neither seem to work. The monitor and gpu are at their latest firmware editions (including the Nvidia’s GPU recent fixes for black screen on boot).
Are Samsung monitors a common theme for folk experiencing these issues?
After reading above that some of the FIBBR cables may be bugged, I am considering running more tests with other standard DP 1.4 cables. What is the maximum cable length (measuring from source through the KVM and to the monitor) that has a good chance of success?
Thanks
Try ferrite chokes at both ends of your cables, that solved black screen issues on everything but my Mac Mini, but I think that might need an EDID repeater because it gets cranky the monitor goes away.
Hi again,
I just wanted to add this extra info to my issue above. The fibbr 3 Inch and 6 inch cables do indeed work with a direct connection between my two samsung neo g8 displays and my 4090, but no signal at all when passing through the dual display, 4 pc dp 1.4 kvm.
(With 3 feet fibbr cables between the monitor and kvm, and 6 feet between the kvm and PC-1 port.
I spent yesterday evening testing with one of my monitors connected directly to the gpu, and trying to pass the second display through the kvm. The monitor through the kvm is indeed detected by Windows 10 in the nvidia control panel, but no display, even when changing the resolution down as far as 4K/60.
Would love to hear cable grand master @wendell ’s perspective on what might be going wrong. My kvm is probably from one of the first batches and I’d appreciate assurances that it is capable of two 4K/144hz. I am also suspicious that Samsung’s latest firmware for the 28 inch neo g70a is buggy, as I recall Wendell mentioning he had reached out to Samsung to fix bugs with their G9 line.
Thanks