5.4-REL random reboots

[Bas Essers]

Hi list

I've read serveral earlier postings about random reboots and a lot of times 
the advice is to check the power supply.
Could this be the power supply in the pc itself or is it more likely the 
power supply of the wall outlet?
The pc that's rebooting is brand new so i think the power supply in the pc 
would be sufficient for all the hardware inside.

What i've tried in order to solve the rebooting problem:
I've applied the patch for the tcp vulnerability as i thought maybe someone 
was exploiting that to cause a DoS but that didn't help.

It seems as if the machine reboots everytime i do something cpu/memory 
intensive, but it also reboots at random when it's 99-100% idle.

I now want to monitor the temperature of the CPU, memory etc, which program 
would you suggest?
I've run memtest for a couple of minutes but that didn't cause a crash.

Thanks

-- 
Met vriendelijke groet,
Bas Essers