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Adding a 7th 4k display to D30

2019-06-11, 11:15 AM


I have NVS510 + K4000, giving 4xminiDP plus 2xDP + 1 DVI respectively. I have 6x 4K TVs 3840 x 2160 (same brand & model) using active miniDP/DP to HDMI adapters and a QHD 2560 x 1600 DVI monitor.


The problem I am encountering is when attaching the 'final' screen. (I have had everything working for some time as above but with only 4x 4k attached to the NVS510 and QHD on K4000 DVI. I am now trying to add 2 further 4Ks to the remaining 2 available DP ports on the K4000. I add the first, no problems. When I add the second and final, I get the problem as described following).


The nub of it - the 7th screen adds and appears in Windows Display Settings and in nView, but doesn't 'display' i.e. the screen appears blank.


I've done several things to rule things out/narrow it down and it seems to me it may be a 'limitation' I'm running up against, perhaps Motherboard PCI slot bandwidth, Windows (using 10 Pro) ability to handle (seems unlikely), NVIDIA Control Panel (seems unlikely) etc.


I've done all the 'obvious' things such as checking hardware installed correctly under Device Manager, all that sort of thing. I'll happily try anything reasonably suggested here, but the issue is so specific and can be extensively described/repeatable that I'm hoping some bright spark can 'see through it'. All Windows Updates installed, Driver using NVIDIA's Driver Installation tool as best latest for the combination of NVS510 and K4000. I've checked the Tech Specs and confirmed 4x 4K is supported on NVS510 and 3 monitors 2x 3840 x 2160 + 2160 x 1600 concurrently on K4000 (although if I'm looking for 'weaknesses' in my fact-checking the blurb says can attach 3 monitors directly concurrently, and says each monitor connection supports the resolutions I'm using, but doesn't explicitly say it can support all three at their max resolutions concurrently. I'm assuming because it doesn't say it can't, it is implied it can. The NVS510 does explicitly state it can support 4x 4K concurrently. 


For info - I have to use NVIDIA Settings for Resolution and select 422 chroma which I guess is a bandwidth issue but it is not a concern to me per se as my use case does not require high screen refresh rate and colour depth, 3D texture etc.


The order in which I have added screens is that the final one I'm adding is a 4k. I've confirmed there's nothing wrong with the hardware e.g. all screens work independently, there is no problem with the active miniDP/DP - HDMI adapters etc. I've tried adding a different last screen - the behaviour is the same so it's not the screen.


When I add the last screen, 7 total show in Windows Display Settings. I can 'manipulate' them i.e. rotate in Setup Multiple Displays etc. 7 total display in nView but the last added one does not add as 'checked'. It appears in the list of displays i.e. it is 'recognised' as being present in the Select displays you want to use: list, but doesnt automatically get a check in the check box (which the others do as I add them, until the 7th final addition). It does not appear in the list of 'available' displays that can be manipulated by nView. It appeas in the Manage Multiple Displays graphical representation as being present, but displays 'fuzzy' ('out of focus') and without a number (i.e. screens 1 - 6 are correctly identified and numbered, but the 7th doesn't have an identity number). When I check the check box manaully in the list of displays I want to use, it allows me to do so and then displays 'not fuzzy' the same as the others and gets a number 7. But the screen itself appears blank i.e. no Windows desktop displayed. When I choose Display - Identify Displays drop-down all displays display the correct numbers except the 'problem' display.


In conclusion - what all this says to me is that there's nothing wrong with hardware, software, drivers etc etc but I'm trying to do something that 'it doesn't want me to do'/isn't supported. When I add the 7th monitor, it is recognised but critically it doesn't get added with a checked check box. Reason? - it seems to be saying 'the monitor has been identified, but not checked to include it in the setup because doing so won't operate properly'. It allows me to 'override' this default behaviour and check the check box to add it manually, and then is 'handled' as expected in Manage Multiple Monitors and is seen as sceen 7, can be moved around etc but it doesn't show in the list for adjusting other Settings such as Resolution etc - I only have screens 1- 6. And nothing gets pushed to the Display itself in a 'told you so, that's why it was added unchecked by default unlike the previous ones, stupid' sort of manner. (Note that when I chose 'Identify', six screens display numbers 2-7 rather than 1-6, which to me seems consistent with Windows and nView recognising 7 displays are attached, but not being able to 'drive' a seventh concurrently, again in a sort of 'here's a clue - number 1 is the screen we can't drive, which you shouldn't have added, told you so'.


I am able to add 6x 4K to the miniDP&DP outputs successfully. I haven't yet then tried to add the QHD to the DVI as the final screen. Perhaps I am already just one final step away from success, but as this has been a rather tortuous exercise I thought I would ask, in case not. 6x 4K at 422 is no problem. 5x 4K + 1x QHD is no problem. If I try to add the 6th 4k to 5x 4K + 1x QHD it recognises it but doesn't add it to my setup & if I add it it can't drive it.


I mentioned that I have to change to 422 chroma for the screens to display nicely (consistent blacks etc). I notice when I do this that there is something seemingly strange about the order in which I do this and getting the settings to Apply successfully. Sometimes I'll apply one and another will revert to RGB then need to be re-Applied. I get there in the end so it doesn't matter - I mention because I'm getting the feeling that the problem, and perhaps solution, lies in a combination of the need to use the lower 422 color setting for what I'm aiming at, the sequence in which I add the monitors and change to 422 without 'exceeding' 'total load' (whatever that is that I'm exceeding. E.g. I can add 1x QHD on DVI, 5x 4K on miniDP&DP, changing each from default RGB to lower 422, but when I try to add final 4k it does so at default RGB and says ' too much, can see it is there but not adding it because can't cope driving that', which it then doesn't. 

As far as I can tell, at a 'simple' level I am not trying to do something that the specs on face-value and as far as I can investigate indicate should work - the motherboard supports 2 graphics cards (I did come across something in the D30 spec sheet somewhere about support for 2 cards that I didn't understand, but it didn't overly indicate what I'm doing won't work - I just didn't understand it - and as far as I can tell the bandwidth should not be a constraint, I'm not using high refresh rates or 3D settings), the NVS510 supports 4x 4K concurrently, the K4000 support 3 concurrently 2x 3840 x 2160 + 2160 x 1600.


I'm thinking that adding that adding the QHD last might work, and the problem might be adding a 4k with default RGB is where/why it is stalling at the final hurdle. Can't add it to change from RGB to 422. Maybe with 6x 4K already at 422, adding 1x QHD not a problem. Or maybe need to change settings whilst unchecked, then add.


I may be barking up the wrong tree altogether, hence asking.


Long post, but hopefully facilitates a short answer and thread, & may help others.






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Re: Adding a 7th 4k display to D30

2019-06-12, 14:51 PM

Very detailed post....I've read it twice and I'm sure there's still stuff that I'm missing.


Assuming you have both GPUs installed in x16 slots, then you're not facing a motherboard/slot bandwidth issue.  Both cards operate at PCIe x16 gen2, and D30 can fully support that with the available x16 slots.


While everything you're trying to do appears to be within the specs of the GPUs, I still have some suspicion that you might be bumping up against the top end capabilities of the GPUs in trying to drive so many high res displays.  


I've gone back and double checked the compatibility matrix for D30, and it does appear that we allowed mixing of these specific GPUs.  That being said, I also wouldn't be surprised if you might be running up against some sort of limitation with mixing of Quadro and NVS. I would have actually expected the issues to track to the NVS510 trying to drive 4 x 4k screens rather than the K4000, so I guess it's good that that part of the config is working OK.


Have you tried eliminating the NVS510 and the 4 displays attached to it from the equation temporarily?  I'm curious if the problem tracks specifically to the 3 display configuration you're trying to run on the K4000, or if the problem only pops up when you go for broke with all 7 screens.


At the end of the day, I think this is likely an issue with the Nvidia software/driver.  From the system side, the cards are enumerating a running as they're supposed to.  So it might be worth trying to play around with different driver versions.  Fair warning though, these cards are on the older side, so I doubt there's been much in the way of driver bug fixes recently.


Lastly, you could also look at trying to update the VBIOS on the GPUs as well.  I don't know the full VBIOS history for these GPUs, but it's probably worth checking to see if there have been any updates pushed out by Nvidia.  



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Re: Adding a 7th 4k display to D30

2019-06-12, 16:57 PM

Hello psuturtle, thanks for taking the time and reply.

Yes that is helpful and the side of things I hoped of in posting on this community - to confirm unlikely a 'system bottleneck' outside the graphics cards themselves - I recall some info about card slot capacities and the like over the years and of course it is a moveable feast, faster cards, faster motherboards, CPUs, more demanding software etc etc. 

Yes they're both in 16 slots. I have some recollection of using nearest to cpu first/for most demanding but may have been hardware-specific.

And seems as mine is dual CPU that adds another teaser, but glad to be able to dismiss it.

I felt I was in danger of info overload with my first post (or way past in danger!) and omitted the info you ask which is, yes I had been running the NVS510 with 4x 4k - in a lower spec machine alongside an NVIDIA Quadro K600 with the QHD screen attached without problems. 

The D30 setup is 'same as' but adding a further 2x 4ks on the 2x DPs the K4000 offers, with more ram per screen c/w the NVS. I'd checked RAM usage on the NVS with the 4ks and running less than 50% and K4000 has almost 3x the RAM per screen.


Meantime as I alluded to I disconnected all screens then booted with only NVS 4x 4ks attached. So I kind of did the reverse of your suggestion to confirm the problem on the K4000, I confirmed no problem with the NVS 4x4K with nothing on the K4000 (because I knew this was good & stable with the K600 & QHD) then added screens to K4000 and the 'seventh screen problem' did not present. So far, it seems stable......


I can't say exactly what made it flounder that caused me to post but I feel you are correct down the lines of the two cards are approved for use together (I'd found a Lenovo model number on the Forum or reference to the combination somewhere before venturing), but are perhaps a little finicky in setup procedure getting them to play nicely together. Get one completely sorted with the other bare, then and only then add screens to the other.


I experienced your sound advice re: drivers along the way also. When I changed from NVS+K600 to NVS+K4000 the NVIDIA tool came up with a newer version which is Enterprise certified or whatever they call it (most robust). Nope. Back to older one.


Thanks for the VBIOS advice - new territory for me so I'll leave as only if needed for now.


Excellent community, excellent support - thank you.




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