I'm mining like 1.7 MHash/s on my Intel 530 internal GPU (6700k), do you think that's quite efficient if I just let that run when the PC is on anyway?
STRATUM OR GETWORK? --
If you are running on a stratum connection, you will get lunch money every week. NanoPool suggests a minimum of 5MH/s for a single miner. With GetWork, you'd be fading in and out, but will still pull in a few dollars a week. If your computer is well ventilated, you should be OK. I don't know how much heat is a problem mining that way. My AMD cards stay under 70 deg C if the room temp is cool. My nVidia cards actually run hotter, they are in closely spaced rigs. nVidia cards still use less energy, though. --scryptr