The problem is that a tbird at 1.2G puts out about 65W of heat (at spec voltage). You need a relatively large HSF just for that, adding a peltier in just pushes the power you need to sink too high for air cooling.
As for temps, my 1.3G runs at about 50C under load tops (that's around 120F), and that's not as hot as they can run. I misfitted the HSF and it ran for several minutes at over 100C before I noticed the temp sensor (then it crashed) and sorted it out.
