Driver 418 + Quadro P4000 rejects EDID mode 2560x1600_60 because pixel clock value is too high

Dear Nvidia Support Community,

We’ve got a fresh install of Ubuntu 18.04 on a new DELL Precision 7820 containing a Quadro P4000 (GP104GL-A). The Nvidia Linux driver 418 is installed via the package available from here:

I’ve got the Quadro connected to two monitors, one with a DP to CRT converter, the other with a DP to DVI-D converter; each monitor has its own X screen. The DP to DVI-D converter connects to a Samsung SyncMaster XL30, which runs at a native resolution of 2560x1600 @ 60Hz, and provides this information via EDID. However, the Nvidia driver is rejecting that resolution. An excerpt from the Xorg.1.log says:

[ 51.626] (WW) NVIDIA(GPU-0): Validating Mode “2560x1600_60”:
[ 51.626] (WW) NVIDIA(GPU-0): Mode Source: EDID
[ 51.626] (WW) NVIDIA(GPU-0): 2560 x 1600 @ 60 Hz
[ 51.626] (WW) NVIDIA(GPU-0): Pixel Clock : 268.00 MHz
[ 51.626] (WW) NVIDIA(GPU-0): HRes, HSyncStart : 2560, 2608
[ 51.626] (WW) NVIDIA(GPU-0): HSyncEnd, HTotal : 2640, 2720
[ 51.626] (WW) NVIDIA(GPU-0): VRes, VSyncStart : 1600, 1603
[ 51.626] (WW) NVIDIA(GPU-0): VSyncEnd, VTotal : 1609, 1646
[ 51.626] (WW) NVIDIA(GPU-0): Sync Polarity : +H -V
[ 51.626] (WW) NVIDIA(GPU-0): Mode is rejected: PixelClock (268.0 MHz) too high for
[ 51.626] (WW) NVIDIA(GPU-0): Display Device (Max: 165.0 MHz).
[ 51.626] (WW) NVIDIA(GPU-0): GPU extended capability check failed.
[ 51.626] (WW) NVIDIA(GPU-0): Mode “2560x1600_60” is invalid.

This seems crazy, because the Quadro P4000 can support 4 monitors simultaneously with 4096x2160 @ 120Hz. I’ve edited the xorg.conf file to disable the pixel clock check. That allows the 2560x1600 setting, but all I get is a black monitor that flickers uselessly.

Is this anything other than a driver bug? If there’s anything I can do to run my monitor at full resolution then please let me know.

Best regards,
Xorg.1.log (287 KB)

This looks more like the converter is not capable of running this monitor, it’s a passive one:

[    51.614] (--) NVIDIA(GPU-0): Samsung SyncMaster (DFP-1): Internal TMDS
[    51.614] (--) NVIDIA(GPU-0): Samsung SyncMaster (DFP-1): 165.0 MHz maximum pixel clock

Edit: for that resolution, you’d need a dual-link dvi.

Aha! This is a subtlety that I was previously unaware of. We’ll try an active converter and see if that fixes it.


Like my edit said, you’d need a DP to dual-link DVI converter. Googling told me that this kind of stuff actually exists, wouldn’t have thought so.

Dear generix,

It is true that I did not specify what kind of DP to DVI-D converter we have. It has a dual-link port, so I expected it to have dual-link capabilities. But it is not active, so it does not support the full resolution. You’ve helped to highlight the particular distinction between active and passive dual-link converters, and so I thank you.