[alligator]

I purchased an SD card reader for my Expresscard slot. It work well, but doesn't read SD cards after the computer has been running a while. Anyone know if this device powers down when not in use? I understand they are hot swapable, so I've pulled the Expresscard out, put it back in, and everything works fine.

Any ideas what's happening?

[mduell]

It'd be helpful to know the brand/model for the SD card reader so we could look it up.

An ExpressCard slot is just PCIe 1x and USB2.0 (your card reader is probably using the latter in the interest of cost); no reason why either of those should power down automatically.

[MrNo]

I have a Belkin multimedia reader and in my experience, the card never powers down.
Even if it does, I never have to take it in and out of the slot to get it to work.

What kind of card are you using?

[alligator]

Belkin - Purchased from the Apple store.

[~bash $]

You know what you should do? Open Console.app (Under /Applications/Utilities/ by default) and check your system.log for any messages that correspond to the times at which you notice the device powering down. It should be something "USB" related, since the ExpressCard is a USB device. This might be a left I/O board issue, and this would help to determine that. Otherwise, I think it is probably the card (either a feature or a problem).