50 is good. 70 is a little high, but there shouldn't be that much of a gap between cpu and gpu. 10 C is the recommended gap. you can create a nand image with the temp thresholds, do it in dashlaunch, or even do it through FSD. 60 degrees C is the suggested number. the 360's cpu can't endure heat as much as the ps3's, but I think gpu/rsx are on par. they both suck. anyway, I think FSD is just fan speed, not technically temp threshold, so be careful with that option. I'd suggest doing it through dashlaunch and making it part of your launch.ini. that way you can change it easily.