CRU / Dell P2720D / pixel clock / add monitor data

[sempronius]

Hi, my first post here :-)


I have a couple of questions regarding CRU:


a) For my Dell P2720D CRU reports a maximum pixel clock of 280 MHz.
To achieve 74Hz instead of 60Hz I created a custom resolution via CRU and succeeded, but the pixel clock value is 291.29 MHz now!
Is this harmful to the monitor, could there be any damage like reducing the life-span of this monitor?


b) I'd like to see the specifications of another monitor that I do not own - the Dell U2719D (V rate, H rate, and especially: max pixel clock, because I do not find the maximum pixel clock for this monitor anywhere!)

Is it possible to add a "foreign" monitor to the list of monitors (top left drop-down list in CRU)? The list shows all the monitors that I had installed before but I cannot add a new monitor that I do not own even if I install its driver.
Is there a way to get additional monitors into this list?



Many thanks

[ToastyX]

The reported maximum pixel clock doesn't really mean anything. There's no way of knowing if exceeding it would reduce the lifespan of the monitor, but usually a small overclock like 74 Hz is not a concern if it displays correctly without any issues.

How would you add a foreign monitor? Where would CRU get the data from? The driver doesn't have that information. CRU gets that information from the monitor. If you have an EDID dump, you can import it with "Import complete EDID" to read the EDID, but that won't add the monitor to the list. Just make sure to press "Cancel" so you don't save the imported data to the current monitor.

[sempronius]

Well, I suppose, using 74hz won't be that much of a problem then.

Okay, CRU gets the information from the monitor itself. I already suspected that, but now I know.
The reason why I asked this is a piece of information I found in a pcmonitors.info review about the Dell U2719D. There the author said that overclocking it from 60hz to 74hz seems to be a mild and safe overclock. I just wanted to see what the maximum pixel clock is, but I cannot find this information anywhere on the internet.


Many thanks for answering so quickly!


/edit
Ah, I forgot to ask...
CRU is able to list the various monitors I had installed before, even if they are no longer connected. So in this case, where does CRU get the information from? From the registry?
Some time ago, I had the Dell U2719D here and it showed up in the list in CRU. But later, I reset everything, so the monitor data got lost and now I can only see the monitors that I connected (and installed drivers for) thereafter. Those monitors not connected right now still appear in the list - so their data is still here as long as I do not reset everything, right?

[ToastyX]

Windows stores the last read EDID in the registry, but only the base block without the extension blocks. Old monitors will remain in the list until removed. Running reset-all.exe removes all EDIDs from the registry.

[sempronius]

Thanks again.

[sempronius]

Another question in this context, maybe...

Since I am still a little worried about using a pixel clock higher than the max pixel clock of 280 MHz (2560x1440@74Hz) I thought about playing games in a lower resolution (1920x1080@74Hz) but using (outside of games) a desktop resolution/refresh rate of 2560x1440@60Hz. - At 1920x1080@74Hz the pixel clock is lower.

I would like to use nvidia's "no scaling" option, though. So I would be playing at a size of 1920x1080, at a refresh rate of 74Hz, but without scaling 1920x1080 to fullscreen; instead I would have black orders, but a sharp image (just like my desktop at 2560x1440)!

Now what I would like to know:
In this scenario (kind of: "1920x1080" inside "2560x1440"), what pixel clock do I have: the one of the 2560x1440 desktop resolution - or in fact the lower pixel clock of a 1920x1080 resolution?


By the way, a less important question:
Why can't my monitor (Dell P2720D) do "display scaling", only "GPU scaling" works, whilst another monitor (HP 27xq) can do both?

[ToastyX]

(03-24-2020 02:25 PM)sempronius Wrote:  Now what I would like to know:
In this scenario (kind of: "1920x1080" inside "2560x1440"), what pixel clock do I have: the one of the 2560x1440 desktop resolution - or in fact the lower pixel clock of a 1920x1080 resolution?

With display scaling, it uses the resolution that you specify. With GPU scaling, lower resolutions are scaled up to the native resolution, so only the refresh rates available at the native resolution will be available.

(03-24-2020 02:25 PM)sempronius Wrote:  By the way, a less important question:
Why can't my monitor (Dell P2720D) do "display scaling", only "GPU scaling" works, whilst another monitor (HP 27xq) can do both?

Display scaling won't be available if the EDID doesn't define any lower resolutions.

[sempronius]

Thanks for your answer.

- Does this mean that when lowering the resolution from the native resolution and selecting "GPU scaling: no scaling" the same pixel clock is used (and maybe exceeded) as when using the native resolution?

- lower resolutions seem to be defined because they are visible as standard resolutions in CRU, but still the "display scaling: no scaling" option does not work, everything is stretched to fullscreen, there are no black borders with the smaller image in the centre (as with GPU scaling: no scaling)

[ToastyX]

(03-24-2020 06:45 PM)sempronius Wrote:  - Does this mean that when lowering the resolution from the native resolution and selecting "GPU scaling: no scaling" the same pixel clock is used (and maybe exceeded) as when using the native resolution?

Yes, it's centered within the native resolution.

(03-24-2020 06:45 PM)sempronius Wrote:  - lower resolutions seem to be defined because they are visible as standard resolutions in CRU, but still the "display scaling: no scaling" option does not work, everything is stretched to fullscreen, there are no black borders with the smaller image in the centre (as with GPU scaling: no scaling)

The NVIDIA dialog is a little confusing. Display scaling sends the resolution to the monitor, so that would depend on the monitor's scaling options. The "no scaling" option applies to resolutions that are GPU scaled, such as the lower resolutions that are automatically added. They would not apply to resolutions defined with CRU unless you use GPU scaling.

[sempronius]

(03-24-2020 07:08 PM)ToastyX Wrote:  The "no scaling" option applies to resolutions that are GPU scaled, such as the lower resolutions that are automatically added. They would not apply to resolutions defined with CRU unless you use GPU scaling.

Hm, I am not sure I understand.

I have *two* options for "no scaling", one for "display scaling" and one for "GPU scaling".

With the Dell P2720D, the "no scaling option" when set at "display scaling" does nothing, but it works when set at "GPU scaling".

With the HP 27xq, the "no scaling option" works in either case.

So, as I see it, there must be a difference between the "no scaling" between "GPU scaling" and "display scaling", or not?