Is a USB-based Wi-Fi adapter worse than a PCI-based one?

[King Mustard]

Just curious.

[AGTDenton]

I've never found USB to be too bad for most things.
I've not used it for gaming though.

You will however have access to more power over PCIe. So higher spec WiFi will be possible and you do have better antennas.

I would use USB where signal strength is good, and PCIe where signal strength is poor.

[Saracen999]

It's a very broad question, and impossble to answer simply. Why?

Which USB? The original, USB2, USB3.0, USB 3.1, USB3.2?

What PCIe spec? PCIe 3, 4? And what's the "times x" bit? Like PCI 3 X4, 3X8, ETC.

And, for that matter, what WiFi? WiFi 5 (802.11n, or ac), WiFi 6 (802.11x, or ax)?

And even then, connected to what? And used for what?

A lot depends on where any restriction or bottleneck might be, and how much demand you'll put on it. For example, if you're connecting a very low-usage device, like a keyboard, then just about any combination of the above will handle the level of throughput you're giving it without even getting winded. In fact, you could probably blindfold it, tie it's legs together and make it hop and it wouldn't get winded.

If, on the other hand, you want a team of several editors all editing 4K video files direct from a NAS, then you're going to max out any combination of the above and really need hard-wired 10Gb or faster ethernet.

Okay, those are extremes, but my point is that if you buy a Formula 1 car to do the 1/4 mile from home to your nearest shop, it's a complete waste. If you buy a 1.0 litre small car and try to F1 race it, you'll get creamed.

The variation of PCIe you use determines the speed of the bus. The x4, x8, x16 bit of it determines how many lanes that bus has.

USB3.2, for instance, is massively faster than USB2, and to fully support what USB3.2 is capable of, you'll want it connected to a wider/faster PCIe bus than a slower/narrower one.

Think of PCIe as a bit like a road, with a speed limit. If the speed limit is 60mph, you can get twice as many cars down it in an hour than if it was 30mph (and you could go no faster than the limit). Raise the limit to 90, and you'll get 50% more cars (assuming you have them driving at the limit, nose to tail, constantly).

But .... stick to the 60mph limit but build 3 extra lanes, and now you can get 4 times as many cars per hour as with the single lane 60mph, and still a lot more than the 90mph single lane.

I'm sure the point is clear by now. You need to know, to answer your question, the max throughput of whichever Wifi you're talking about, to see whether it saturates or exceeds whichever USB you're talking about, and then, whether that combination saturates whichever PCIe slot you're connecting to, bearing in mind ultimately, USB data ends up going up and down a PCIe lane to/from the processor. It just might not be one to which you have access via a mobo slot.

And then, finally, does what devices you want to connect, and what data will result, challenge whichever WiFi, USB and/or PCIe combination you're talking about. You could use a Formula 1 car on a 16-lane motorway to get to the local shop, if you're connecting a keyboard, but I doubt you'll get there any quicker than on a pushbike down a cycle path, or dirt track. But if you're trying to back up your PC to a fast USB-connected SSD, you don't want to limit it to a cycle path.