I have a Win10 LTSC 2019 system with i7-7700 processor and HD Graphics 630 GPU. I'm trying to run two monitors at 1920x1080 with the primary set to 60Hz and the secondary to 120hz.
I'm finding the secondary monitor is limited by the refresh rate of the primary (i.e., both are running at 60Hz) despite setting the display configuration to 120Hz for the secondary monitor. The secondary is connected to the DP port and the primary to the DVI-D port. If I swap primary/secondary then I can get 120Hz on the one monitor, but these monitors are part of a larger system and it is really desirable to have the secondary one at 120Hz.
I'm looking at using an MST hub to alleviate the issue - but am not completely confident that will fix it for me.
Trying to avoid going to a discreet card as this has implications on EMC certification, regulatory approvals, testing & support as well as long-term peripheral availability.
1) Should the secondary monitor refresh be capped by the primary?
2) Is there some configuration options I've missed to allow a higher refresh rate on the secondary?
Thank you for your reply. Please find the file you requested attached to this message. You are correct that there is a video conversion to get the DVI-D. It is sourced from the HDMI and on the AIMB-505 from Advantech is limited to a max resolution of 1920x1080 @ 60Hz.
The two monitors are not identical. one is the ASUS VG248 and the other the ASUS VG279. Note that these are just the monitors I happen to be testing with as they are capable of 120Hz, and not the monitors we would necessarily deploy our product with.
I would not characterize the issue I'm having as 'following' the DVI. Rather, the secondary monitor's refresh rate is limited (capped) by whatever the primary monitor's refresh rate is. This is true regardless of which monitor is primary and whether the primary is using DP or the converted DVI. For example:
Primary monitor on DVI set to 1920x1080 @ 60Hz. Set secondary monitor (on DP) to 1920x1080 @ 120Hz. Refresh rate on secondary monitor is capped at 60Hz.
Primary monitor on DVI set to 1280x1024 @ 75Hz. Set the Secondary monitor (on DP) to 1920x1080 @ 120Hz. Refresh rate on secondary monitor is capped at 75Hz.
Primary monitor on DP set to 1920x1080 @ 50Hz. Set the secondary monitor (on DVI) to 1920x1080 @ 60Hz. Refresh rate on secondary monitor is capped at 50Hz.
Refresh rates were checked using 3 methods but the 2 main ones were testufo.com and an in-house system that uses a photo-diode measurement of an avatar drawn to the screen.
Our desire (nay, expectation) was that we would be able to drive a secondary monitor connected to the Display Port at 120Hz without going to a discrete card.
Any suggestions you can offer to achieve our objective is appreciated (I have an MST Hub on order and will be trying it next week).
I have/had no expectation that the VGA-DVI connected monitors would do anything but be limited to the maximum specified by Advantech. I was surprised to find that the primary monitor's refresh rate was a cap on the refresh rate for the secondary monitor. I do not know what (or who) is causing the cap. I can get 120Hz as long as the monitor on the DP connection is set as the primary.
Yesterday I received a MST Hub and found that if I connect *both* monitors to the DP connection that the refresh rate of the primary still limits the refresh rate of the secondary. I.e., Both monitors on DP, primary set to 60Hz, secondary set to 120Hz and I still only get 60Hz on the secondary. On the positive side, I have found that I can set both the primary and secondary to 1920x1080 @ 120Hz when using the MST hub and I do, in fact, get 120Hz on both. Now I still need to dive into a latency that seems too high and figure out why the occasional frame is being dropped... but that's another story.
The problematic behaviour (the refresh rate set for the primary monitor creates a refresh rate limit on the secondary monitor) is the same regardless of whether the DVI connection (converted from HDMI) is used for the primary monitor, the secondary monitor or completely avoided by using DP for both monitors through the use of a MST hub. It seems far more likely that a common component is the cause of the problematic behaviour under these various conditions.
Last week I had updated OS and, after encountering the issue, updated to the latest video drivers.
Thank you for your time,