Well, I must say that I have all the same problems with TBS-6985 and nothing helps.
I have enabled MSI interrupts. I have tried to disable IR. I have tried another computer with different CPU/chipset. I have tried another PSU. I have tried different PCIe slots.
Nothing helps.
I started with tvh 3.6 but it was impossible to use more than one tuner.
When I switched to 3.9 it got better. I was possible to watch two channels at once... sometimes. Sometimes not.
But the biggest issue is that I get constant "Tvheadend disconnected" messages. Sometimes it happens more often. Sometimes less often. Sometimes it takes 10-15 seconds to reconnect, sometimes it takes minute or more.
And testing/bad status is still a problem sometimes.
So, I can say that this setup is unusable.
I even thought about switching to VDR. It's really difficult to setup, compared to tvh. But the show stopper was xvdr/vnsi plugin and different versions. I just could not find matching versions for server and clients.
Before 6985 I had 3 tuners: Technotrend S2-3200, Hauppauge HVR-1100 and some cheap rtl2832u USB. Everything was ok. But with 6985 it just does not work.
Now I have TBS-6985 and Hauppauge Nova-T. When I watch something that comes from Nova-T it seems ok. But TBS-6985 is just so unstable...
Is there anything else I could try?
Opensource driver is not a solution (yet). It does not work with 6985.
Or should I just sell it (if anyone even wants to buy it)... and go with some other card?