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Old 2004-02-17, 19:08   #3
Reboot It
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Aug 2002
London, UK

3·31 Posts

In a nutshell: most of the heat comes from Prime95 using the CPU (processor) to its maximum all of the time. Most PCs are hardly using any of their potential CPU power, but Prime95 is so well written and carefully optimised that it pushes the CPU to its limit, and as this uses much more electrical power than usual, it generates much more heat. This is behind the temperature increase you have noticed.

Note also that by default Prime95 writes checkpoint files (a temporary note of the result so far) to the hard disk every 30 minutes. This gives it something to go back to in case the PC crashes or the application is not shut down in an orderly way. Because of this, if you set the HD to power down every 20 minutes, it will only need to spin up 10 minutes later. This will increase the mechanical and thermal strain on the HD enormously, so I suggest you don't do this. (You can increase the time between checkpoints, but then you risk losing more work if Prime95 has to go back to the latest one: the tradeoff is yours to make.)

I would look very carefully indeed at your cooling - it isn't a good idea to run Prime95 on a PC inside a closed case. The heat may eventually damage some part of the PC. I would say you need to leave the cabinet doors open 24/7, and even then the airflow may be noticably impeded by being inside the cabinet.

Last fiddled with by Reboot It on 2004-02-17 at 19:09
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