There could be a reason you want an USB3 card reader in your PC. In general, you'd better opt for an external unit, regardless if it is USB2 or 3, and simply plug it in an available USB port.
But let's assume you want one...
Actually, there are some situations. In my latest build I used an older case that only featured USB2 ports, and I wanted a (full speed) USB3 port for an external drive, easily accessible from the front. I also use an older camera, and I find it convenient to have a cardreader in my PC that supports Compact Flash as well as SDXC (for smartphones etc.).
Besides that, this specific case features USB slots on the top... which is quite inconvenient when the machine is standing under a desk.
I had an internal USB3 connector available on my Asrock AB350 Pro4 mainboard (all USB2's were occupied), so I started to look into an USB3 card readers. Which often have problems, it seems. Too many horror stories, so what to do?
Problem: these USB3 readers often do not work (after a while)
The problem is: many USB3 card readers simply do not work, or are of such a seriously cheap quality that little usage breaks them. Also many seem to work at first, but fail or disappear after a while. I consider reliability worth a few bucks, so was willing to pay a little more for something that causes less frustration.
I gambled, and paid a few euro more. This Akasa unit seems to work fine, and seems to be sturdy enough. Pay some attention when inserting CF cards though, they go in upside down (compared with the units I was used to).
This thing is about twice as expensive as the cheaper units you can find. You have to decide for yourself it that is worth it. I've seen this Akasa reader for around €25 in the Netherlands.
No, not going to do your typical YouTube unpacking videos... unless someone starts paying me for that 😁
Cardboard box. Standard stuff. 'Nuff said. Good though is that it shows the kind of connector you need on your mainboard. Please note: this thing requires a USB3 connector!
This unit has two additional holes which allows it to be mouned a little more forward than usual. Great if you have a non-standard case such as mine.
Everything seems to work fine. A USB3 connecter on a mainboard is technically TWO USB connections on a single connector. It's not very surprising that the USB3 on the front is simply a straightforward extension of one of the two ports on the mainboard.
I am not sure the card reader slots all run at full USB3 speed. I have not done any speed tests, but it doesn't seem to be any faster than the USB reader in my previous machine. It could be the memory cards themselves (so far I tried SD, SXHC and SDXC and FC) but it doesn't matter much, as the unit does what I need it to do: offer me a conveniently located USB3 on the front, as well as CF and SD(XC) slots. Speed was not a key element. Stability was.
There's an older version using an USB2 connector for the mainboard, and an external USB3 connector for a regular USB port. Make sure you buy the right one. I read some reviews where people complained about it damaging files or SD cards. Nothing like that happened here thus far. (Then again, you'll typically only find negative reviews on the Internet, so who knows.)
Mine seems to work fine. Only time will tell if it stays that way.