I'm using Linux Mint and am trying to install a TP-LINK TL-WN851ND PCI wifi card. The card is definitely seen by the computer as it's listed when I do a lspci and the ath5k and ath8k drivers appear to be installed but it's not giving me an options to enable the card (neither does the status light flash).

Any ideas anyone?

Meaning what exactly ?. "modprobe -l" finds them or "lsmod" finds them ... or ?.

Might be worth checking if ath9k is available. I would think so for recent/current Mint but haven't checked.

I ran sudo athload which told me that it was uninstalling ath5k and ath8k and then ran sudo ath5k which told me that it was installing ath5k and ath8k.

AR9227...

I own one of these cards and it reports its chip as an AR9227, requiring the ath9k module. I can configure the card under openSUSE 12.1 but the card causes a system freeze shortly after making a wireless connection.

I find through the Internet that am not alone with this card and this problem.

How did you manage to configure the card?

The kernel...

The kernel module "ath9k" should be loading when the card is detected. Try the command "lsmod | grep ath9k" to see if this is the case. Otherwise, try "modprobe ath9k" to load the module. Remember to blacklist any other module.

In addition, you have to use your NetworkManager applet to find and and configure the connection to your wireless signal. There are several posts on the Internet for Ubuntu based linux distributions and devices/chips using this module.

I am using openSUSE 12.1 and it provided all that was needed to get the TL-WN851ND card working. As a test, I booted a Mint 13 live-DVD and the card was found and configured and I could establish a connection to my router, but then too the system froze right after I opened an Internet site.

The use of the "ath9k" module assumes that you are making a connection to an 802.11n network. 802.11g seems to require using the "ath5k" module. You can try loading each in turn while blacklisting the others. Google will tell you more.

lsmod | grep ath9k doesn't give anything!

modprobe ath9k gives -

WARNING: All config files need .conf: /etc/modprobe.d/ndiswrapper, it will be ignored in a future release.
WARNING: Error inserting cfg80211 (/lib/modules/2.6.28-11-generic/kernel/net/wireless/cfg80211.ko): Operation not permitted
WARNING: Error inserting mac80211 (/lib/modules/2.6.28-11-generic/kernel/net/mac80211/mac80211.ko): Operation not permitted
FATAL: Error inserting ath9k (/lib/modules/2.6.28-11-generic/kernel/drivers/net/wireless/ath9k/ath9k.ko): Operation not permitted

I don't know...

Are you running the latest version of Mint? Try to boot a live-cd/dvd of Mint 13 and see what happens. This card should install and connect. It may freeze after that, but that's another problem and may have to do with which kernel module to use use on a g or n network.