←back to thread

Optical PCIe 7.0 connection hits 128 GT/s

(www.tomshardware.com)
204 points WithinReason | 6 comments | 17 Jun 24 11:42 UTC | HN request time: 0.205s | source | bottom
Show context
yjftsjthsd-h ◴[18 Jun 24 00:02 UTC] No.40712649[source]▶
So I guess what this makes me wonder is: Why are we using electrical signals to connect the data lanes between components and computers these days, rather than moving everything to optical for data movement (obviously power would stay electrical, but that's already on separate lines)? I assume there's an element of cost, and once the photons get where they're going they have to be turned back into electrical signals to actually be used until such time as we get around to getting pure light based computers working (someday but not yet...), but that must not overwhelm the advantages or we wouldn't be looking at this being developed.
replies(7): >>40712677 #>>40712948 #>>40713112 #>>40713271 #>>40717224 #>>40717847 #>>40720156 #
1. lazide ◴[18 Jun 24 01:45 UTC] No.40713271[source]▶
Changing from light to electricity (and vice versa) is relatively slow, expensive, and cumbersome.

Additionally, we don’t have a decent way of transferring significant power over fiber optics.

So since everything has to have copper power fed to it anyway, unless there is some compelling reason (like distance) to make optical/fibers disadvantages worth it, copper only is usually simpler and better.

At least for now.

replies(1): >>40720192 #
2. hinkley ◴[18 Jun 24 17:33 UTC] No.40720192[source]▶
If memory serves the original plan for Light Peak was power wires and shielding braided around a fiber optic core.
replies(1): >>40722267 #
3. lazide ◴[18 Jun 24 21:17 UTC] No.40722267[source]▶
Hence why we ended up with USB-C cables.

Less fragile, similar data rate, simpler BOM, less sensitive to dirt and debris, plenty of power.

replies(1): >>40722877 #
4. hinkley ◴[18 Jun 24 22:44 UTC] No.40722877{3}[source]▶
What's the minimum bend radius for plastic fiber these days?
replies(2): >>40723684 #>>40727106 #
5. pezezin ◴[19 Jun 24 01:00 UTC] No.40723684{4}[source]▶
Around 10 mm for OS2 cables.
6. lazide ◴[19 Jun 24 11:11 UTC] No.40727106{4}[source]▶
Larger than ‘getting kinked in a desk drawer’. Though smaller than when the market made the decision of course.

You still need the copper wires to do power delivery, so either you end up with an even thicker cable, or multi-purpose the copper cables for signaling too.