I have your same GPU's and have had your same issues, multiple times.
Here are my suggestions to alleviate driver crash:*Use the AMD 14.3 Drivers
*Try these settings:
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
cgminer.exe --scrypt -o [your info] -u [your info] -p [your info] -g 1 -w 512 --lookup-gap 2 --thread-concurrency 24500 -I 20 --gpu-powertune 20
Important: Save these settings in your batch file. After you've saved your batch file, launch MSI afterburner. Set your core clock to 1000 and your mem clock to 1250, save your settings to profile 1 and click "apply over clocking at system startup." After that, go into the settings for MSI afterburner, and check off that the program launches at system startup.
These steps will keep you from getting your clocks stuck and continuing the driver crash issue even after system reboot.
*When you get the "driver has crashed..." message, you can't just restart the computer, you need to shut it off via the PSU switch and then reboot.
*Make sure you are running nothing else on your rig except for SGminer/CGminer and MSI afterburner.
These steps should have you hashing around 820-850 kh/s with the Tri-x cards and stable. If you are unable to achieve stability with these steps and settings, it is probably a power issue. Exactly what PSU are you using?
*I would also strongly suggest updating your motherboard BIOS.
You can review a thread I posted where I was having the exact same issues as you are with the same setup:
http://www.overclock.net/t/1476740/i-may-have-just-fried-3x-r9-290Lastly, don't give up and don't assume your cards are toast. You will figure this out, its just going to take a lot of patience and a lot of work. Trust me, I've been there.
