Intermittent USB power shenanigans

I recently just built a new PC and it features such new fangled things as USB 3.2, USB C and even USB 4.

I also treated myself to a new card reader to take advantage of these new ports.

Be careful with the Sandisk pro reader.  This one is UHS2 up to 300MB/s, but the version without the CF slot (so microSD and SD only) is only UHS1.  You can get up to 200MB/s with specific Sandisk cards, but UHS2 cards read at under 100MB/s

It turns out USB is a bit of a mess.

On the back of the PC, it has blue USB A ports which are USB 3.2 gen 1 = 5gbps

It also has some red ports which are USB 3.2 gen 2 = 10gbps

It also has USB C which is USB 3.2 gen 2 = 10gbps

But don't go thinking USB C and USB A 3.2 gen 2 are the same.

When the card reader arrived, it had the shortest USB C to C cable you've ever seen.  I'm not exaggerating if I say it was only about 15cm long.

The only spare cable I had that was long enough was my Nintendo Switch pad charging cable - USB A to C.

That worked fine, but it was only a USB 2.0 cable data wise, so I ordered a good quality A to C cable from amazon capable of the 10gbps speeds (unnecessary for the card reader, but it's always good to have fast cables in case you want to use them for something else)

I plugged the new cable into the same blue USB socket and into the card reader, then it started freaking out, disappearing and reappearing.

I couldn't figure it out.  Was it the cable? Or did I just waste £100 on a buggy card reader?

I decided to ask Gemini about it.  I detailed the behaviour and asked if there were any known issues with this card reader or my motherboard.

None - but what was revealed to me is that it was down to the choice of cable.

The short of it was, it was a power delivery issue.

The Switch cable worked because it put the card reader into USB 2 mode.  In USB 2 mode, the power provided by the port was sufficient.

Moving to the USB 3 A to C cable is what caused the problems because now the card reader is operating in USB 3 mode, but the USB A ports (red or blue, doesn't matter) don't deliver enough power.  I instead had to get a USB C to C cable, because USB C can provide more power.

Same data transmission standard (A to C and C to C can both be USB 3.2 gen 2) - but the available power depends on the physical connection you use (should have called it USB 3.3 if the base power specs change).

Since switching to a USB C to C cable, it's been flawless, though it means I've had to give up a 10gbps port for a 5gbps device.

I mean who would expect a simple card reader to need more power than a USB 3 A port can provide?