50C is ok for a CPU I would think with all the other components and proper venting 50C (122F) for AMBIENT air is a little high. I don't think you have any worries about your cpu as most modern cpus (read:several years old) will shut down before they hit critical temps. Your other hardware, however won't. So if it's just your cpu that's running hot but the cab is venting and the ambient is lower than 50C I would say you were ok, but hell another quiet intake fan never hurt.