I managed to get this working using a 10ft and 3ft version of this cableand chaining them together.
For USB, a friend of mine recommended this cable as it worked fine for him. However, I'm needing to use the Vive link box like others suggested here to get it working, whereas my friend did not. It could be that I needed a longer cable than they did. They mentioned only needing to extend by 10ft. Could also be that my motherboard is a few years old, right when USB 3.0 was coming out.
However, since getting it setup I've finally had to plug in headphones and have discovered that the headphone port on the headset if very loose and I'm getting no left channel audio out of it. So I need to get a replacement headset. :(
https://www.amazon.com/gp/product/B00L1K1KDE/
This one works fine for me, the amazon basics USB 3.0 extender seems ok as well.
Cable Matters DisplayPort to DisplayPort Extension Cable (DP to DP Extension Cable) 10 Feet I used to go about 15 feet on the vive with an HDMI extension cable.
Like I said, initially when it didn't work I blamed the cable, but I tried connecting the DP cable directly to the video card and still using my USB extension and it still didn't work right (if it worked at all).
I was just glad that I still had the Vive link box set up so all I needed to do was use it as a go-between for the USB and that did the trick.
Just an update. I finally updated to the latest Pitool (144) and my delock cable no longer works at 90hz full FOV. I had to switch to the 10ft cable matters one that many others have linked and that works flawlessly.
https://www.amazon.com/gp/product/B00L1K1KDE/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
I have the Pimax 8k, and I have almost an identical setup as you.
I am daisy-chaining the 10-foot and 6-foot version of these cables for a total of 16 additional feet (on top of the original Pimax cable). It works perfectly.
For the USB cable, I'm using this extension from my PC to the Vive Link Box (with the original USB cable that came with the Vive). I'm then plugging the Pimax into the USB port of the Vive link box. It also works perfectly.
With all this put together, I have approximately 31 feet total for the video extension, and 30 feet total for the USB extension. I've never had connection troubles, no snow or image problems, and I've never dropped connection.
Just an update. I finally updated to the latest Pitool (144) and my delock cable no longer works at 90hz full FOV. I had to switch to the 10ft cable matters one that many others have linked and that works flawlessly.
https://www.amazon.com/gp/product/B00L1K1KDE/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
I'm using this set with no issues so far with the 5k+: https://smile.amazon.com/gp/product/B00C7SA21U/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
https://smile.amazon.com/gp/product/B00L1K1KDE/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
https://smile.amazon.com/gp/product/B00FT9VW0O/ref=ppx_yo_dt_b_asin_title_o03_s01?ie=UTF8&psc=1