2 ms·

Something that keeps needing to be pointed out every thread this stuff appears on: What these tools report are not functionally different from just believing "w

Something that keeps needing to be pointed out every thread this stuff appears on: What these tools report are not functionally different from just believing "what's on the packaging", despite the misleading marketing claims. These tools read a chip called an "eMarker". These eMarkers are programmed to say whatever the manufacturer wants them to say - there's no requirement that the information be based in reality. Plenty of cables have eMarkers that claim "40Gbps" or whatever speeds, or support 240W PD...but absolutely cannot deliver either of those. And none of these consumer level software or hardware testers can actually test either of those claims. They can only take the cable's own claims at face value. Resistance measurements can cursorily test claims of 240W but resistance changes with temperature which changes with current...so unless your tester puts 5 amps down the wire for 5 minutes and then tests resistance it's not a very good test. AFAIK none of the testers flow 5 amps through the cable. Actual maximum data throughput is very hard to know. The only way to really "know" how much data can flow through a cable is with an expensive oscilloscope or cable tester. Because 80Gbps cables run at ~13GHz, at minimum you need a 26GHz scope (Nyquist–Shannon sampling theorem) or more practically a 52GHz scope. And it turns out it's really expensive to measure electrical signals 52 billion times per second. The necessary devices start at $15,000 (cable signal integrity tester) [0] on the very low end and only work for max 10Gbps USB 3.2 cables, or past $270,000 for 80Gbps USB4 cables (proper 60GHz oscilloscope) [1]. On the high end, each signal integrity test device can actually cost $1-2 million [2] where the base unit starts at $670,000 plus then spending additional money for hardware-accelerated analysis, specialized active probes, and the specific PAM-3 / USB4 compliance software packages. 0: https://www.totalphase.com/products/advanced-cable-tester-v2/ https://www.totalphase.com/products/advanced-cable-tester-v2... 1: https://www.edn.com/12-bit-oscilloscope-operates-up-to-65-ghz/ https://www.edn.com/12-bit-oscilloscope-operates-up-to-65-gh... 2: https://www.eevblog.com/forum/testgear/uxr1104a-infiniium-uxr-series-oscilloscope-110-ghz-4-channels-price/msg1839848/#msg1839848 https://www.eevblog.com/forum/testgear/uxr1104a-infiniium-ux...

vel0city 1mo ago
While I totally agree if you want to truly know the quality of the signal you need a very expensive box to actually measure the tiny deviations, if the question is "can this thing handle 80Gbit of data", can't you just get a couple of USB4 chips or whatever and have one send a pattern at that throughput and have the other try and receive and confirm that pattern? That would give you a basic "yes/no" kind of answer of "can it send XGbit?" I agree the processing capacity for such a thing at retail isn't likely to be $40, but probably a good bit less than >$15k. After all, you can get <$1,000 laptops that can do that pretty easily. For example, I don't need to precisely measure exactly how messed up the signal is to know if the HDMI cable works or not at a given resolution. I'll see the TV have issues displaying a picture. Either the picture is there reliably or its not. I'm not trying to fine tune the cable, I'm just trying to see if it generally works or not. As for testing power delivery, its not that electrically complicated to put a few amps through a wire for a few minutes. That said, the user must be aware if the cable isn't up to the standards that the chip states you could have some serious issues on your hands, but I guess better to find out on the tester at the workbench or desk than at your bedside.
- nerdsniper 1mo ago
  Sure. But the cable tester that you describe here doesn't exist. You could maybe DIY it but there's none off the shelf.
VorpalWay 1mo ago
> Actual maximum data throughput is very hard to know. The only way to really "know" how much data can flow through a cable is with an expensive oscilloscope or cable tester. Couldn't you just do a data transfer test over the cable and check the error rate? At least in theory, the controller might not report enough I guess.
- budman1 1mo ago
  If you are just wanting "to use it", sure. If you are building a cable for a specific purpose, or want to actually ensure that it will work, use test equipment. IT interconnect closet vs. air vehicle.
  - vel0city 1mo ago
    > If you are just wanting "to use it", sure. Isn't that what most people here are really wanting? I don't imagine most people here are seriously wanting to know the exact extreme measurements, just "can this cable reasonably do what I need from it? Does it do what it claims on the label generally?"
    - ssl-3 1mo ago
      People don't want "reasonably do". They want "resolutely do". They don't say it like that, but: They sure do get grumpy when the Thunderbolt-connected display for their laptop shits the bed mid-afternoon on a Wednesday after a year, or the export for their recording session fails on a device they've done this with dozens of times before, or the cable connecting the camera they use to watch their cats no longer works: They get quite grumpy about these things, indeed. So they want resoluteness, not reasonableness. I know it's 2026 and many of us are used to using bots that are compulsively high-confidence liars. But just go ahead and try to reason with someone about a local computer that fails tasks apparently-randomly. That's the makings of a bad scene. :)
      - vel0city 1mo ago
        I'm just meaning people here are looking for a "does it work", a binary yes/no. Not a precise measurement of exactly how perfectly the digital signal is making it through the wire. They don't care exactly what the SNR is or whatever, they just want to know when they plug in the cable for a given need will this cable work? You don't need a six figure oscilloscope or logic analyzer to know "does it work".
seanw444 1mo ago
So basically, it's cheap for them to defraud the consumer, and prohibitively expensive for the consumer to adequately protect themselves from it. The absolute state.
registeredcorn 1mo ago
For people who cannot, or do not want to spend fantastic amounts of money on cable testers, can you name any reliable cable brands that, generally or strictly, sell cables which match their marketing material? I don't need absolute perfection, but I hate the idea of buying an expensive cable, and being lied to about how good the performance is. I don't mind paying more for quality, but its hard for me to really articulate any difference between two USB cables, except by maybe their length, and how "sturdy" one might feel compared to the other. It wouldn't do a lot to solve the issue of various low quality cables I already own, but I wouldn't mind throwing money at a cable company that doesn't lie to its customers.
- nerdsniper 1mo ago
  I go for anything that’s USB-IF certified. Personally the Amazon Basics USB4, 40Gbps, 240W are great price for value whenever they’re around $10: https://camelcamelcamel.com/product/B0C93G2M83 https://camelcamelcamel.com/product/B0C93G2M83 At that price they’re my default “generic” cable. Unless I need a longer length or 80Gbps this is the main workhorse in my home. It’s nice just never worrying about discerning “charging” cable from “data” cable. CableMatters is a very reputable brand if you need more variety in selection. Monoprice also seems to care about quality. CalDigit and Apple both have vested interest in providing quality cables. Strong brand is a good starting point, but even then I still try to stick with USB-IF certified offerings only.

vel0city 1mo ago

While I totally agree if you want to truly know the quality of the signal you need a very expensive box to actually measure the tiny deviations, if the question is "can this thing handle 80Gbit of data", can't you just get a couple of USB4 chips or whatever and have one send a pattern at that throughput and have the other try and receive and confirm that pattern? That would give you a basic "yes/no" kind of answer of "can it send XGbit?" I agree the processing capacity for such a thing at retail isn't likely to be $40, but probably a good bit less than >$15k. After all, you can get <$1,000 laptops that can do that pretty easily. For example, I don't need to precisely measure exactly how messed up the signal is to know if the HDMI cable works or not at a given resolution. I'll see the TV have issues displaying a picture. Either the picture is there reliably or its not. I'm not trying to fine tune the cable, I'm just trying to see if it generally works or not. As for testing power delivery, its not that electrically complicated to put a few amps through a wire for a few minutes. That said, the user must be aware if the cable isn't up to the standards that the chip states you could have some serious issues on your hands, but I guess better to find out on the tester at the workbench or desk than at your bedside.

nerdsniper 1mo ago
Sure. But the cable tester that you describe here doesn't exist. You could maybe DIY it but there's none off the shelf.

VorpalWay 1mo ago

> Actual maximum data throughput is very hard to know. The only way to really "know" how much data can flow through a cable is with an expensive oscilloscope or cable tester. Couldn't you just do a data transfer test over the cable and check the error rate? At least in theory, the controller might not report enough I guess.

budman1 1mo ago
If you are just wanting "to use it", sure. If you are building a cable for a specific purpose, or want to actually ensure that it will work, use test equipment. IT interconnect closet vs. air vehicle.
- vel0city 1mo ago
  > If you are just wanting "to use it", sure. Isn't that what most people here are really wanting? I don't imagine most people here are seriously wanting to know the exact extreme measurements, just "can this cable reasonably do what I need from it? Does it do what it claims on the label generally?"
  - ssl-3 1mo ago
    People don't want "reasonably do". They want "resolutely do". They don't say it like that, but: They sure do get grumpy when the Thunderbolt-connected display for their laptop shits the bed mid-afternoon on a Wednesday after a year, or the export for their recording session fails on a device they've done this with dozens of times before, or the cable connecting the camera they use to watch their cats no longer works: They get quite grumpy about these things, indeed. So they want resoluteness, not reasonableness. I know it's 2026 and many of us are used to using bots that are compulsively high-confidence liars. But just go ahead and try to reason with someone about a local computer that fails tasks apparently-randomly. That's the makings of a bad scene. :)
    - vel0city 1mo ago
      I'm just meaning people here are looking for a "does it work", a binary yes/no. Not a precise measurement of exactly how perfectly the digital signal is making it through the wire. They don't care exactly what the SNR is or whatever, they just want to know when they plug in the cable for a given need will this cable work? You don't need a six figure oscilloscope or logic analyzer to know "does it work".

seanw444 1mo ago

So basically, it's cheap for them to defraud the consumer, and prohibitively expensive for the consumer to adequately protect themselves from it. The absolute state.

registeredcorn 1mo ago

For people who cannot, or do not want to spend fantastic amounts of money on cable testers, can you name any reliable cable brands that, generally or strictly, sell cables which match their marketing material? I don't need absolute perfection, but I hate the idea of buying an expensive cable, and being lied to about how good the performance is. I don't mind paying more for quality, but its hard for me to really articulate any difference between two USB cables, except by maybe their length, and how "sturdy" one might feel compared to the other. It wouldn't do a lot to solve the issue of various low quality cables I already own, but I wouldn't mind throwing money at a cable company that doesn't lie to its customers.

nerdsniper 1mo ago
I go for anything that’s USB-IF certified. Personally the Amazon Basics USB4, 40Gbps, 240W are great price for value whenever they’re around $10: https://camelcamelcamel.com/product/B0C93G2M83 https://camelcamelcamel.com/product/B0C93G2M83 At that price they’re my default “generic” cable. Unless I need a longer length or 80Gbps this is the main workhorse in my home. It’s nice just never worrying about discerning “charging” cable from “data” cable. CableMatters is a very reputable brand if you need more variety in selection. Monoprice also seems to care about quality. CalDigit and Apple both have vested interest in providing quality cables. Strong brand is a good starting point, but even then I still try to stick with USB-IF certified offerings only.