The chipset doesn't know anything about 802.11ac standard -- but it doesn't have to; all it has to do is support the downstream mini PCIe connector that the WiFi/BT solution is plugged into. After that, it is the drivers for this solution that provide the necessary information.
Before you run off and purchase an 802.11ac card to plug into your system, you need to find out if the system will even support such a card. What I am getting at here is that many (in my opinion, slimy) system vendors implement Whitelists in their BIOS. If the card that is plugged in isn't found in this Whitelist, the BIOS will not support it (and will disable it so that the O/S cannot see it). This is their (slimy) way of making sure that you purchase your solution only through them (at some inflated price, of course). Now, I am not saying that your system actually implements such a Whitelist. What I am saying is that you need to contact your system manufacturer's support desk and find out from them whether such a card will be supported by this system.
Hope this helps,
Thanks for that Scott. I was already aware of the BIOS whitelisting issue, just wanted to take the next step as I had read somewhere that the HM65 chipset wouldn't support the 802.11ac standard. Must have been an uninformed person like myself. I've contacted the manufacturer...let's see if they respond.