Random noise instead of desktop - HDCP related?

I have a Dell XPS 13 laptop, which has only USB-C ports for everything. I also have the Dell HDMI / DisplayPort adaptor, which works fine on my smart TV. I really wanted to use the laptop with an Iiyama monitor, but the adaptor only outputs random noise. I don’t get any error message, but I’m assuming this is because my old monitor isn’t HDCP compliant.

To be clear, I’m not trying to watch protected content, this happens even with an empty desktop, whether I’m running Windows 11 or Linux Mint.

I’m thinking the Startech * CDP2DVIUCP would be a better bet - I know that HDCP can be enforced over DVI, but it’s not very commonly done.

However I can’t be sure whether it’s the adaptor or the laptop itself which is refusing to work. I don’t get an error message on either OS.

The CDP2DVIUCP isn’t expensive, but any opinions would be welcome before I buy.

Hello @Bienzani,

Thank you for posting for the first time here on the StarTech.com community page.

We are happy to advise on which adapter will be right for you.

The part that stands out to me most in this description is the fact that the monitor only outputs random noise. Can you confirm the Iiyama monitor works with other devices or video source connections?

While I have come across some HDCP output that can be static or random noise, usually the output is a black screen or an error message. Normally I would not expect copy protection to be an issue with Windows or Linux systems unless protected content is being viewed.

If you do not have another DVI video source and you wish to test with the CDP2DVIUCP in place of the Dell HDMI / DisplayPort adapter it can certainly be worth trying. If you do not have another device with DVI, but have access to a system with HDMI, a simple cable adapter like HDDVIMM1M may be worth trying too.

I might suggest reviewing the specifications and the display settings too, just to be sure the correct output resolution and refresh rate are set for the monitor. Occasionally there may be issues where older and newer devices may not cooperate to transmit the correct information when they are first connected, so the display settings can certainly be worth checking.

If you wish, I can look into this further for you. Could you share a few more details?

  1. The specific model or generation for the Dell XPS 13
  2. The model of the Iiyama display
  3. How the Iiyama display is recognized in the Windows display settings.
    • Specifically the resolution and refresh rate
  4. The same display information may be helpful to review in Linux too.

Please let us know how you wish to proceed and share any details you can and we will be happy to advise you further.



Thanks for your time @DavidF. To be more precise about the symptoms I see, the monitor continually cycles between random noise for ~8s and showing the desktop for ~2s.

The monitor has been working fine for years on a variety of sources - DVI mainly, but sometimes HDMI or even VGA as the need arises. I usually have it connected to a KVM switch which uses DVI connections.

  1. The Dell XPS13 is a 9315 - I don’t think it’s the latest model.
  2. The monitor is an Iiyama PLE2607WS - again, far from the latest model. :slight_smile:
  3. Windows correctly reports the display type, with a resolution of 1920x1200 @ 59.95Hz.
  4. Linux gives the same info.
    (The monitor’s info screen also reports 1920x1200, but at 60Hz which I assume is a rounding error!)

I’m puzzled by the lack of an error message - I’d expect the laptop to produce one, even if the monitor didn’t know what HDCP was. I used to work on digital video systems before retirement, so it may be that my experiences have coloured my diagnosis and HDCP isn’t to blame, but I can’t think of another candidate.

I suppose my problem is that I’m trying to run a professional set-up on an amateur’s budget. :slight_smile: I’m just wary of buying another display adaptor only to find that it won’t do the job either - however they aren’t expensive and that may be the only way to find out for sure.

Hello @Bienzani,

Thank you for getting back to me with the model information for your computer and devices. DVI adapters are normally simple solutions, so it is god to ensure that you are not using extra resources if you do not need to. Consider some additional tests before you purchase a new adapter too.

After taking a few moments to review the specifications from Dell Iiyama the specification that stands out to me is the notes about the sync timing in the Iiyama product information for this monitor.

Older DVI monitors, particularly specialized monitors, can have non-standard timings. I am curious if there may be some compatibility issue with the timings in this particular combination of devices. For example, this monitor appears to support refresh rates up to 75Hz, but if the USB-C adapter does not support refresh rates higher than 60hz, perhaps it is not interacting correctly the appropriate lower refresh rate?

Can you check if other resolution or refresh rates are available when testing in Windows and Linux? I would be curious if other refresh rates and resolutions work better.

If that still does not work then you may certainly want to test with another adapter like the CDP2DVIUCP. Perhaps even an inexpensive USB-C to VGA adapter like the CDP2VGAFC to see if analog video output might overcome a possible video sync issue. Again, if indeed this is the nature of the issue.

I hope these suggestions help! Please get back to us with the results of your tests. I am interested to see if I am correct about the sync or timing compatibility.


Hello @DavidF,

The nominal 60Hz refresh rate is the only one that’s offered, but I can set lower display resolutions down to 800 x 600 and none of them work, in Linux or Windows.

Just for “fun” I dug out an old Iiyama PLE431S-W1S which did work on the Dell adaptor at 1280 x 1024, and I could set refresh rates of 60Hz or 75Hz. That at least reassures me that my system isn’t fundamentally opposed to older monitors.

I remember that 1600 x 1200 @60Hz represents a pixel clock of 162MHz, close to the limit for single-link DVI, and achieved by special timings as you say. At work we were careful to test our systems up to that resolution because it would be the most taxing.

On that basis, I can be reasonably confident in trying a CDP2DVIUCP. Being a dedicated DVI convertor, it should be ‘aware’ of the limitations where an HDMI convertor such as the Dell may get confused. I’ll report the results in case the info may be helpful to anyone else.

Thanks again for your suggestions. I still don’t fully understand what’s going wrong, but I can suppress my engineer’s instincts if I end up with something that works. :slight_smile:


Very good! It sounds like you are on the right track.

I am optimistic that the DVI adapter will help and look forward to your results.

Thank you,


The CDP2DVIUCP arrived today, and - it works. I still can’t explain what was going wrong with the original set-up, except that it wasn’t HDCP, and I owe Dell an apology for leaving an inaccurate review. :slight_smile: On the other hand, the monitor’s EDID should have included the timings it was capable of accepting, and the HDMI adaptor should have respected them. Nor can I explain why the monitor showed random noise instead of an error message about incorrect timings.

No matter, it works, and this adaptor appears to be a good route to using an older monitor with a USB-C video port. Thanks to @DavidF for the advice!

Hello @Bienzani,

I appreciate you replying with these results, and I am happy I could help!

By the description, it did not seem like an HDCP error. I have seen HDCP errors represented as static output but usually there is an HDCP note on screen too.

We do have internal notes indicating that some older model DVI monitors can have specialized timings, but I cannot say that I have seen this kind of thing come up for me very often. EDID may communicate the timings, but there could be any number of other factors affecting the performance. Though I am no engineer, I am quite technical and I could speculate that either the adapter or the graphics card was trying a best-effort approach. If that is a reasonable way to describe it.

No matter what was occurring with the other adapter, I am very glad that the CDP2DVIUCP worked for you. I was not 100% certain that it would, but I am often impressed with what our products can do!

Please do start another thread if there is anything else we can do to help.