Decoding now working - But problems remain

Following on from my last post and my JT65 problems after installing a new sound card, it is sort of fixed but I cannot find the root cause.

I tried removing the new sound card and doing a system restore to get the system back to the same state as it was prior to installation of the new card. The problem with JT65 remained, it would not switch to decode.

I also tried HRD DM780 to decode PSK, however this also was not working and could not decode, so not specifically a JT65 problem.

My next step was to switch the radio interface from the original motherboard sound to the new sound card and it worked. JT65 would switch to decode and was decoding stations as usual.

So whilst I have not fixed the problem, decoding applications do not work on the original, motherboard soundcard, they are working with the new soundcard.

What I do not understand is why JT65 would not switch to decode and why this is soundcard dependent. I assumed it was a timing function with JT65 switching to record after 49 seconds (hence the need for accurate PC timing).

The new Soundcard is an ASUS Xonar DS and the motherboard is the usual Realtek. Operating System is Windows 8.