weird restarts when compiling

[Aggelidis Nikos]

Thanks for your answers Manolis and Mike. In the beginning i didn't
suspect hardware because it happened only at compilation procedures.
Now i realize that every other task i do isn't really demanding.

> Look through /var/log/messages.
i get this: Jul 13 09:00:00 apollo newsyslog[1018]: logfile turned
over due to size>100K

* CPU overheating
-> Is there anyway to check for cpu temperatures within freebsd?
-> I 've used the pc for like 8 hours in a really hot day but it
didn't restart...if this can be considered as an indication.

*Memory
-> i used memtest ,from an ubuntu live cd, to check the memory and
everything works fine according to it.

*PSU
I have a 400Watt PSU... maybe this is inadequate. I will try to swap
it for something stronger to see how it goes.

In general where are there any stress tests i can do, to test the PSU
and some major subsystems of the computer?

thanks in advance,
nikos

PS: this was a ready-made pc that had it's p4 processor upgraded to a
dual core. It also got a new motherboard and 2G of ddr2. It has an old
nvidia GeForce fx 5200, and a 400watt nameless PSU. I only have
freebsd,which i installed a month ago, on it.