MacOS – SD card reader does not work after upgrading to Mountain Lion

It might be that the majority of the OSes that people virtualise (or at least those doing so with Parallels) can only use 4 GB of RAM anyway because they are 32-bit OSes, so it would not be necessary to have more than that. You shouldn't need more than 4 GB of RAM in the virtual machine anyway, so you partly answered your question. The majority of laptops these days don't have a massive 16 GB of RAM like you do; Parallels is only looking at the market side of things there.

If you really need more, why don't you just Boot Camp (you can Boot Camp with Linux as well); that way, you will use all of your computer's power if you need it. With your SSD, it won't take too long to restart.

The first step is to open system information and see if anything shows for that device.

Next would be to install a clean OS on to a USB drive or back up and erase the Mac / reinstall the OS. You could try a safe boot, but I've not seen that make any difference for the SD card slot even though it could help if you had an oddball kernel extension conflict.

Also, be sure to test your SD cards on another computer or reader as it would be a shame to have that be the issue and have to restore a backup to find out that was the issue.