Just started messing with this today.  I am using a brand new Alienware with the Dual GTX880M setup (16GB total) GDDR5.

If I use the executable from the x64 directory it detects both GPUs and it must be doing something because the machine all but locks up but it never submits any shares (scryptguild).

Going to the x86 directory it starts right up and hashes without error but I am only getting a combined 390-400Khs.

Will keep at it and post findings.

Hi, i have a problem with my rig.. Windows 7 find correctly all gpu ( 4 palit 750 ti oc) but when cudaminer start the driver crash or sometimes crash all the system and appear a blu and white windows and after the pc reboot. I use powered riser and so i don't think that the problem is the power or the voltage..
With only 3 gpu the rig works fine..

Setup:
4 gtx palit 750 ti
mobo https://www.asus.com/Motherboards/M4A79XTD_EVO/#overview 
windows 7
4gb ram
Psu corsair Rm 850 Gold
riser usb powered
Drivers 335

Someone can help me??

Thanks you guys

You need more ram.  6gb might work but 8 is recommended if you want stability.

I run a 6 card rig just fin with 4gb of ram.

All of 'em -- Anything cudaminer or ccminer runs.  
No problems.

Are you OCing? I run fine also with 4gbs with 3 750tis on scrypt,scryptn, and jane (with risers), but when I mine heavy or groestl with the same OC settings they all crash. Putting them back to default stock speeds fixes it.

With 750tis? Everytime I OC them with heavy and groestl my drivers crash or bsod with the same OC settings as I have for my scrypt/scyptn/jane coins which works flawless. Maybe its the vers of ccminer or type of 750ti, but id doubt that. I have the EVGA SC and MSI TF 2gbs running on latest ccminer release 0.5. Either way dont really see too much of a difference with my hashrate OCing with heavy/grosetl algs. Usually get around 12/13MH heavy.