I've got a system much the same as you, have the fans installed as you do. Front fan is at the base of the tower, rear fan is about CPU level in back - I use the stock AMD cpu fan/heatsink. I live in Phoenix and keep my house about 82-85F in the summer. System runs fine as long as the room temp is about 83F or lower, CPU temp stays below 125F (barely). Systemboard temp is well below that (about 95F I think). Above 83F (room temp) it is fine unless I am running a CPU intensive program (games) - Real work doesn't tax it much (figures). I've hit about 135F a few times before I noticed - can't say it has caused any adverse affects yet.