First of all thanks for your extensive contributions to this subreddit. New Valve Index user here, and I purchased both of your linked cables for my extension purposes. Unfortunately the one you linked for power here does not fit the Index's wall adapter, its female end internal needle is too large for the hole inside the Index's wall adapter's male needle.

From the valve developer community: "The dimensions for the female plug (PSU side) are 3.5mm Outer Diameter (OD) and approx. 1.1mm Inner Diameter (ID) and for the male socket (HMD side) are 3.6mm OD and 0.9mm ID. A most common 3.5mm/1.35mm plug/socket DOES NOT FIT! Thank you Valve for using such a rare and uncommon size!"

On the hunt for a 3.5mm/1.1mm extension cable. Amazon seems to only have one here and it's OOS, and of the two reviews one said it worked for their index cable, one said it damaged their index cable. Only other option I've found was Walmart Canada...

Edited for clarity.

it's very nearly correct. definitely need displayport and usb3, the power is a barrel jack.

• the trident cable is what plugs into your computer's displayport, usb3, and the power adapter on one end and the index hmd's cable on the other.

• the trident is 1m in length (the hmd's cable is 5m)

• the wall wart's (power adapter) cable is approximate 3m, so you have ~2m of play there.

• usb3 is usually good for an extra 1-2m without anything more than a good quality cable. much more than that you'll need something active¹

• the problem is that 6m (1m trident + 5m hmd cable) is at the edge of displayport spec, so extension requires something more than just a passive cable... it absolutely needs something active¹ to be reliable.

• extension by 1-2m falls in a bad zone because it's going to be just as expensive to do so for a longer run ax most of the cost is in the active electronics.

• that said, this 5m combo displayport/usb3 extension is $50 and works well.

  • you might be able to get a little bit cheaper going with a separate signal booster/repeater, shorter dp cable, and shorter usb3 extension... but there's a very real possibly of this route costing you a few days of returns and trying different combinations/brands of cables.

• so your signal path is going to look like: computer -> extensions -> trident + power -> 5m hmd cable -> headset.

• with respect to power, i recommend just using an outlet closer to where the trident ends up.

  • if this doesn't work for you, you can use a regular ac extension cord with the wall-wart at the end.
  • otherwise, a 3.5mm barrel (not headphone) extension such as this ~3m one will work [see post below, this is not the correct size and we are waiting on confirmation of the correct one], although these cables often have a sloppy fit: a bit of tape might be necessary.
    • this will work with shorter runs, but i'd say you're likely to get into trouble (voltage drop) after 6-10m or so. this is my guesstimate, as i haven't run the numbers or tested it... but my guestimates are usually pretty good.

and that is all she wrote!

i think i'll be adding this to my tips and tricks guide, so if anyone has any comments/criticisms/additions, or simply wants to argue with me, please post 'em! i don't strive to be right, i seek to be accurate and useful.

thanks for reading, and thank you /u/ganglore for getting me off my keister to write this :)

1: active vs passive:

• passive is just a wire. think extension cord. cheap, easy, and understandable.

• unfortunately, when we get to higher speed signals like displayport and usb3 with angry pixies electrons whizzing to and fro hundreds of millions to tens of billions of times per second, life (and physics) gets rather complicated.

• let's make a metaphor construct a useful lie:

  • think of shouting down a 5m tube: the person on the other side will hear and understand you just fine, although they might question why you are aiming a 5m tube at their head.
  • now think of shouting down a 100m tube. the person at the other end will likely hear something, but it probably won't be decipherable.
  • what arrived at the other end of the 100m tube is a bit of power, but the signal is scrambled beyond recognition.
  • when you are trying to send a lot of information in a short amount of time (high information density), it requires a good signal.
    • think talking really, really fast down a tube instead of slowly enunciating every syllable.
  • but at some point, the length of the tube becomes too long to carry your really fast speech reliably.
  • one solution is to talk slower. this unfortunately doesn't work for vr, which is highly dependent upon lots-o-data as quickly as possible².
  • so we need something to go somewhere in the middle of our too-long tube and listen to what you say, then repeat it into the remainder of the too-long tube.

• and thus we've arrived at what an 'active' cable is: one that actively boosts the signal somehow. as you can imagine, it needs a bit of power to do this and some extra electronics. this is why they cost more.

• we have 2 major types of active cable:

  • copper, which isn't a very good tube, so you need a repeater every ~5m or so.
  • fiber optic, which is an excellent tube, so once you convert the angry pixies electrons into light (photons), you can go a very, very long way... but you have to convert the photons back to electrons at the other side.

• alternatively, you can get a booster and a short passive cable, but this is usually just as (or more) expensive than an active cable.

  • if you think about it, an active copper cable is a booster + passive copper cable all-in-one.

2: direct mode: this is so important valve ended up working with nvidia and amd to get their displayport outputs to send slices of a frame as they're rendered instead of waiting until the frame is done then sending it. this helps cut latency down, and is a significant part of why when you move your head the displays instantly update without perceivable lag. this is called motion-to-photon latency, fwiw.