If I was to setup a mining machine with quad 750 Ti's powered by a sempron 145, would 4gb of ram be enough to run ccminer efficiently, or would 8gb be needed?
I started out with 4GB and had some problems in Win7 x64, but with some changes to the ccminer it helped a lot when running multiple instances. Since I upgraded to 8GB (6x 750ti) I haven't had any problems at all.
Currently though, when up and running the machine is only using about 2GB.
I don't think it is 'required' right now to have more than 4GB, but honestly I wouldn't want to risk what could happen in the future over what amounts to ~$25 in RAM.