Asus or tplink pci-e wireless cards?

While the Asus quotes a 600Mb/s speed, the TP-link's 450Mb/s is single band only, so you could get that on both bands. Of course, your router wouldn't match either likely (if it can even do 5GHz). And if it could, it would only be useful for internal transmissions - your internet connection won't handle that.

Go for the cheaper.