Lessons Learned: Flickering Fix + USB-A / Display Port -> USB-C Merging Cable

Hello all, I recently purchased and installed Combo USB-C Power Delivery & DisplayPort 1.4 KVM - Triple Monitor

When I went to install this, I realized that it was my PC’s previous GPU that had the USBC port, not my current one.

I was about to pull the trigger on LevelOneTechs USB-C Combiner: DisplayPort and USB to USB-C (store(dot)level1techs(dot)com/products/p/dp-repeater-hdmi-splitter-6sha9-yznx5-zm58w), but then recalled I had already purchased a cable for my portable touchscreen monitor that merged USB-C and DisplayPort (amazon(dot)com/dp/B0BKG23KTK?psc=1&ref=ppx_yo2ov_dt_b_product_details). With this cable, I was able to confirm that both the data (keyboard, mouse, USB audio) worked without issue, and the DisplayPort did show on the monitor (Samsung G9 Ultrawide). However, with this cable, I did have the flickering that many other users had previously mentioned.

Recalling that flickering had also occurred previously on my Valve Index VR Headset, and that issue was solved by wrapping the cable numerous times through the center of a couple(4x) of ferrite toroid cores (amazon(dot)com/gp/product/B084JQ7ZK3/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1), I decided to use the cores I had on hand, did the same for this cable, and my flickering was fixed.

I didn’t experiment much with other cables or smaller, cheaper ferrite toroid cores because I was using what I already had on hand, but other combinations may also work. Also be aware that with this configuration, while USB does work through the USB-C connection, it only uses a USB-A 2.0 connection on the computer side. While this is fine for low-bandwidth applications like keyboard, mouse, game controllers, and USB audio, it will likely be quite slow for data transfers to USB mass storage devices. If you need quick data transfers, I recommend trying the USB-C combiner from the Level1Techs store linked above.

Of course, your mileage may vary, but for anyone struggling with either of these problems, this info might be useful, so I thought I’d give back to this amazing community by sharing. I hope it helps.

Apologies in advance for the terrible formatting. I was not allowed to post this including hyperlinks.

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