I would like to underclock my CPU, but I think it is not possible. Indeed I have an old Intel Celeron which is not Mobile or anything :

cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 2
model name : Intel(R) Celeron(R) CPU 2.60GHz
stepping : 9
cpu MHz : 2600.238
cache size : 128 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe up cid xtpr
bogomips : 5214.59
clflush size : 64
I really tried _everything_ and still am unable to get my CPU underclocked (and therefore a cooler system).

I recently had an idea but I don't know if it's possible to do it : I would like to modify the kernel scheduler to add something like a "sleep" in the main loop in order to slowdown the CPU usage.
I don't care (at all) if this leads to bad performance, I really want to avoid the PC to completely stop because the CPU temperature is too high.

I would really appreciate any of your ideas. Thank you.