I have tried to install different drivers for the cards, and I have tried installing a previous version that supports both cards. Neither worked. It seems to be the combination of the new card and anything but the new driver that makes GUIMiner not start.
Now, when I am running only the new card, Phoenix and Stratum Proxy, it stopped working tonight, a few hours after I started it. I restarted the miner this morning and it worked again. I hope it's a one time occurance, but I doubt it. It didn't happen with Phoenix and BCPool. Any guesses?
My estimsted rewards seem to be about right. I'm not exactly sure what they should be, but they are not in the 7 satoshi order of magnitude... Currently it's 0.00051612 and I've been running 200 MHash/s for 1.5 hours.
Maybe you should use next workaround. Remove one card from a computer. Run cgminer and if it works you will get kernel for that card. If it doesn't work change SDK and run again. If hashrate is too low use diffident SDK/driver and remove .bin file from cgminer folder. When you find the best combination backup .bin file just in case. Now remove the card and put in other card. Do the same but don't delete first card .bin file only second card .bin file if you don't like hashrate. Now put both cards in and run cgminer. It might work.
And just in case. When running windows you need to plug monitor or null plug into card. Did you?
I have not got any miner working on it's own without GUIMiner, I have tried a few different miners and lots of different settings in the command line, both own ideas and found on the internet. Always one of two things happen: either the program exits/crashes/doesn't start, or it runs but gets 0 hashes/s. This when GUIMiner works, I haven't even tried it when it doesn't.
Why wouldn't GUIMiner even start if it was only needing a monitor? I had a monitor connected to the other card at some time, but it was not connected to electricity as I didn't have any more outlets and didn't feel the need for two monitors enough to dig up an outlet splitter. Does the sensing need power to the monitor, or is it just two connected pins or a resistor between two pins or something?
The other day, I also noticed the problem of low payouts. For some time, it was down to one satoshi.
I still get the problem with GUIMiner stopping, just saying "connecting...", but it only happens around once every two days, so it's managable. I think it's my Internet connection that's unstable, and GUIMiner somehow can't recover when the connection goes down temporarily.