Been using HDAV1.3 for one year without incident. Have been OC'ing new motherboard (EVGA 4Way Classified) and CPU(I7 960) for last few weeks. no other changes. Had been fine before OC'ing. Now mobo does not recognize it. Actually RMA'd sound card but replacement does the same. How do I get mobo to recognize card. it powers up properly. Have tried different PCI-E slots. Disabled on board audio. Removed CMOS battery for reset.  Running stock speeds on everything.  Have 2EVGA GTX480's SLI'd and everything's watercooled.

On board sound really sucks in comparison. Can anybody help?

Creative X-Fi titanium had a similiar issue for me I had to use the original drivers disc to get the MB to recognise the sound card. Just downloading the drivers wouldn,t do it for some reason. Have you used drive sweeper by any chance? That can clean to much sometimes who knows I reinstall a fresh OS every 7 weeks or so .I tinker alot,hope this helps good luck.

make sure your memory gap setting in bios is set right, otherwise some pci cards refuse to work

i think 1.5G, after that you can try 2.5G if neither help just set it back to auto

jboudwin

Neither of those settings worked and neither did rolling back drivers.  Will re-install OS today.

DON'T re install OS yet ! I had a similar situation. Try this first: remove all software for sound card. Shut down but don't restart. Take sound card  out of the computer. Start computer without soundcard. Let windows fully load (so windows knows the soundcard isn't there) Shut down, put the card in and restart windows. Windows should now find the card. Reinstall the software for the soundcard and you should be all set.

OOOOOOOHHHHHh My God!!!  I got it...found my fix.  I'll detail it especially since my problem has occured to others.  Hopefully my deadends and errors will help someone else.
 
Tried to play an online game and had no sound...hadn't played in a few days.  In that interval I had updated BIOS and Win 7 SP1 loaded (automatically).  Tried many options as noted including RMA'ing card, two OS installations, and new sound card (it's going back).
 
Apparently sound cards (not just Xonar) have had problems of randomly failing to be recognized.  The driver refuses to load or install.  This is due to overwriting of the EEPROM.  This website has the fix: 
http://www.alsa-project.org/main/index.php/Xonar_EEPROM_Failure
 
On first OS install I neglected to disable automatic updating (so it updated) and could  not tell if SP1 was the cause.  Reinstalled again but this time remembered to disable updating and all I connected was the sound card to ensure no other conflicts.
Found in Device Manager a yellow triangle with exclamation point at PCI Standard PCI to PCI Bridge.  Double clicking it says "This device cannot find enough free resources that it can use".  Disabling various devices did not free up any resources.
 
Some fixes online suggested changing IRQ's or disabling COM ports.  This lead me to...an EVGA posting... about updating the EVGA 758 BIOS.  In BIOS under "PnP/PCI Configurations" is "Reserved RC for Bridge".  On that BIOS it is "Enabled" but not on the BIOS that I just updated on my 762 mobo.  I enabled it and HALLELUJAH!!!!  XONAR HDAV IS RECOGNIZED.
Took a lot of pissing and fuming to get this.  Hope others don't have to.  And thanks to everyone that offered advice.

Thanks.  No hair left but it'll grow back.