|I totally disagree with techninja. There's absolutely nothing wrong with overclocking provided you do it wisely. Generally, if you overclock too much, the only "bad" things that will happen is either the system will become unstable or it simply won't boot, in which case all you'd have to do is dial down the overclock settings. Modern CPUs have built-in thermal protection so it's virtually impossible to overheat one to death. There's very little risk of hardware damage unless you start jacking up the voltage settings.|
I'm curious how you managed to overclock an Acer board in the 1st place? The majority of OEM boards come with a BIOS that's so crippled that the only way to overclock is via software.
As for the issue with the fan, did you replace only the fan or did you replace the heatsink as well? If you removed/replaced the heatsink, did you remove all traces of the old thermal material & apply a fresh dab of paste according the the directions for your particular CPU? If it's an AMD CPU, you should have put a tiny dab in the center of the CPU, then set the heatsink on top of it & locked it down. The dab should be approx the size of a grain of rice, the size of a bean is too much. If you used none at all, too much, or spread it on like frosting a cake, that could be the problem. Also, make sure you're plugging the fan into the proper header on the motherboard & that the fan plug has the correct number of pins. Some boards have an RPM sensor; if no fan movement is detected, the board will not boot.
One last thing, the board does not need a CMOS battery to work. The only reason the battery is required is to retain the BIOS settings in the CMOS chip when the power cord is unplugged. A board will work perfectly fine with a dead battery or no battery at all, but the date/time & other BIOS settings would have to be reconfigured after every shutdown.